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OpenGL Voxel Cone Tracing Experiment - Part 2 Progress

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Interesting results, I think it's time for you to get a more complex scene to evaluate your implementation. It would be nice to see that running on a room scene or some exterior scene with walls and buidlings around you.

 


The area is currently only limited to this scene (i'm using a single 64x64x64 3D texture), but I intend to have a go at this "camera-centred cascades" idea to see if I can get consistent interactive framerates for a much larger scene. The main concern I have with using cascades is that it involves dynamically shifting the volume texture, thus leading to large scale flickering. This flickering is evident when I move around emissive objects in my current implementation.

 

Yup, I can confirm that camera centered cascades will result in large flickering. I've tested that my self on my own implementation of Voxel Cone Tracing and I can say that it simply doesn't look good.

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Yup, I can confirm that camera centered cascades will result in large flickering. I've tested that my self on my own implementation of Voxel Cone Tracing and I can say that it simply doesn't look good.

 

hmm...

I'm thinking now that cascades do not have to be camera-centred. I might have an alternative idea.

Edited by gboxentertainment

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hmm...
I'm thinking now that cascades do not have to be camera-centred. I might have an alternative idea.

 

What do you have in mind?

 

If you are thinking about keeping the volume centered on the camera but snapping it to the voxel grid then I can tell you before hand that it doesn't solve the problem either. My approach did that and there was still lots of flickering when the volume changed position. smile.png

Edited by jcabeleira

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YMMV? Snapping to voxel grid positions after N number of steps/distance works fine for almost all of the flickering I've had. How are you voxelizing the scene?

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What is quality difference of screenspace reflections vs just using cone tracing reflections? Also have you tested voxel space ambient oclusion?

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What is quality difference of screenspace reflections vs just using cone tracing reflections? Also have you tested voxel space ambient oclusion?

 

I imagine both are dependent on voxel resolution. Which reminds to point out Directed Acylic Graphs for Voxels: http://www.cse.chalmers.se/~uffe/HighResolutionSparseVoxelDAGs.pdf Which seems like a fantastic win for reflections and thin object problems both.

 

I also don't remember any flickering in Epic's Elemental demo, despite some quite vast areas using cascaded octree levels. I can't remember if they mentioned flickering being a problem though.

Edited by Frenetic Pony

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YMMV? Snapping to voxel grid positions after N number of steps/distance works fine for almost all of the flickering I've had. How are you voxelizing the scene?

 

This actually describes a much better way of understanding a possible implementation of my idea.

As well as doing this, I am thinking of using something similar to partially resident textures (because most of us, especially with nvidia hardware still are not able to use them yet).

We piece together multiple smaller high-res textures, together with larger lower-res textures to simulate cascaded partially resident textures.

The biggest problem is that there may be texture seams between texture edges which cannot be hardware filtered (this must be done manually).

Has anyone tried this yet?

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I also don't remember any flickering in Epic's Elemental demo, despite some quite vast areas using cascaded octree levels. I can't remember if they mentioned flickering being a problem though.

 

 

I'm pretty sure the flickering problem shouldn't occur with octrees - the main reason being that instead of sampling directly from a 3D texture, they aren't limited in their filtering method to offset the sampling by each voxel. With octrees, they can offset by half a voxel, if I understand Crassin's paper correctly.

Edited by gboxentertainment

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I think Frenetic mentioned to me once about something that I guess would be called "Voxel Temporal Anti-aliasing".

I tried to implement it but couldn't get it working - but now that I think about it - I only tried it for the lowest level voxels (highest res).

Majority of the flickering actually occurs at mid-level.

 

I think the way to implement it is to fade in/fade out the color of adjacent voxels based on the position of the object within each voxel so that it smoothly interpolates instead of jumping from 0 to 1.

 

Has anyone tried something like this yet?

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I'm pretty sure the flickering problem shouldn't occur with octrees - the main reason being that instead of sampling directly from a 3D texture, they aren't limited in their filtering method to offset the sampling by each voxel. With octrees, they can offset by half a voxel, if I understand Crassin's paper correctly.

 

They don't have any flickering because the octree allows them to store the entire voxelized scene. Their lighting is stable because they don't need to have a moving voxel volume that only covers the scene partially. However, the octree is probably impractical for many games because larger scenes may not fit inside the 512x512x512 texture they use to store the voxel bricks.

Edited by jcabeleira

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I've just re-viewed the original UE4 walkthrough demo (back from when they were showing off their fancy new lighting tech - which they later removed and covered up) and noticed that there is flickering in the reflection of the gold statue on the floor when he moves it. The emissive object that he moves around (the fire hammer) also flickers but its hard to differentiate that from the flickering effect that they purposely used. There's also some noticeable flickering of the indirect lighting when he moves the "spotlight planet" around. I never actually noticed any of this before.

 

I then went to have another look at Crassin's video and paid close attention to the hand's reflection on the floor when he demonstrates the specularity control - I had to pinpoint the exact moment, but it flickers! This occurs most abruptly when the specular cone ratio was turned to medium, but when it was either high(diffuse) or very low(reflective), then its smooth.

 

So it seems that the solution to this problem is neither to do with octrees or voxel resolution or filtering, which is good for me because it doesn't really give too much incentives to using octrees.

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What is quality difference of screenspace reflections vs just using cone tracing reflections?

 

For a true comparison, I turned up the voxel resolution to 256 (left) and turned off any fade effects from the ssr (right).

 

[attachment=18166:giboxvct.png][attachment=18167:giboxssr.png]

 

To tell you the truth - I am simply just using SSRs to fake reflections that I cannot yet achieve with VCT (but one day in the future I may be able to).

 

The biggest issue that I can't seem to figure out with my VCT reflections though, is the transparency. I'm not sure if this is anything to do with the way I filter my voxels.

Each ray should terminate when it accumulates full opacity. So when a ray hits the surface of the orange box it should terminate when it detects that its opacity is 1, but it doesn't, instead, it continues on, accumulating everything that is behind it.

 

Here's the specular cone tracing code if anyone wants to analyze it:

vec4 specConeTrace(vec3 o, vec3 d, float coneRatio, float maxDist)
{
	vec3 samplePos = o;
	vec4 accum = vec4(0.0);
	float minDiam = 1.0/voxDim;
	float startDist = 2*minDiam;

	float dist = startDist;
	while(dist <= maxDist && accum.w < 1.0)
	{		
		float sampleDiam = max(minDiam, coneRatio*dist);
		float sampleLOD = log2(sampleDiam*voxDim);
		vec3 samplePos = o + d*dist;
		vec4 sampleVal = sampleSpecVox(samplePos, -d, sampleLOD);

		float sampleWt = (1.0 - accum.w);
		accum += sampleVal * sampleWt;

		dist += sampleDiam;
	}

	accum.xyz *= 2.0;

	return accum;
}

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        float sampleWt = (1.0 - accum.w);
        accum += sampleVal * sampleWt;

There is bug. With full opaque voxel you get zero value for sampleWT. Or am I missing something?

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What is quality difference of screenspace reflections vs just using cone tracing reflections?

 

For a true comparison, I turned up the voxel resolution to 256 (left) and turned off any fade effects from the ssr (right).

 

attachicon.gifgiboxvct.pngattachicon.gifgiboxssr.png

 

To tell you the truth - I am simply just using SSRs to fake reflections that I cannot yet achieve with VCT (but one day in the future I may be able to).

 

The biggest issue that I can't seem to figure out with my VCT reflections though, is the transparency. I'm not sure if this is anything to do with the way I filter my voxels.

Each ray should terminate when it accumulates full opacity. So when a ray hits the surface of the orange box it should terminate when it detects that its opacity is 1, but it doesn't, instead, it continues on, accumulating everything that is behind it.

 

Here's the specular cone tracing code if anyone wants to analyze it:

vec4 specConeTrace(vec3 o, vec3 d, float coneRatio, float maxDist)
{
	vec3 samplePos = o;
	vec4 accum = vec4(0.0);
	float minDiam = 1.0/voxDim;
	float startDist = 2*minDiam;

	float dist = startDist;
	while(dist <= maxDist && accum.w < 1.0)
	{		
		float sampleDiam = max(minDiam, coneRatio*dist);
		float sampleLOD = log2(sampleDiam*voxDim);
		vec3 samplePos = o + d*dist;
		vec4 sampleVal = sampleSpecVox(samplePos, -d, sampleLOD);

		float sampleWt = (1.0 - accum.w);
		accum += sampleVal * sampleWt;

		dist += sampleDiam;
	}

	accum.xyz *= 2.0;

	return accum;
}

 

Why are your voxel reflections transparent?

 

EDIT: Nevermind. I need to read first.

Edited by Chris_F

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Okay, so I'm going to answer my own question about the transparent voxel reflections.

For diffuse reflections (or glossy but not clearly reflective) I had to divide my alpha samples by a factor (say 10 in this case) during filtering, otherwise ugly voxel artifacts occur on the surface - as seen below on the sphere and the red wall (which are glossy but not entirely reflective - specular cone ratios of 0.4).

 

[attachment=18175:giboxvct2.png]

 

The floor, which has a specular cone ratio of 0.01, is now showing clear reflections without transparency.

Of course this scene only runs at about 7fps because I turned up the voxel resolution to 256 to demonstrate the effect.

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Heh, I'll ask again since it seems my question was skipped: how are you downsampling your voxel data? This might play a role in the issue you're having.

Edited by Styves

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Another reason for the transparency is that you are sampling the voxels along the view ray but none of the samples hits the exact center of an opaque voxel so they never achieve full opacity. This is because the voxel volume texture is configured to use bilinear filtering so whenever you sample an opaque voxel without hitting its center you get a partially transparent result that is the interpolation between the opaque voxel and the neighboring transparent ones.

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Heh, I'll ask again since it seems my question was skipped: how are you downsampling your voxel data? This might play a role in the issue you're having.

 

I'm pretty certain I've solved my issue. But for your interest:

The same method that this guy uses:

http://www.geeks3d.com/20121214/voxel-cone-tracing-global-illumination-in-opengl-4-3/

 

I use hardware mip-mapping and then filtering with the compute shader by transferring values for each 3x3x3 voxels to neighbouring voxels in each direction.

 

Btw, I've also posted a video at the bottom of the start of my thread.

Edited by gboxentertainment

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I think Frenetic mentioned to me once about something that I guess would be called "Voxel Temporal Anti-aliasing".
I tried to implement it but couldn't get it working - but now that I think about it - I only tried it for the lowest level voxels (highest res).
Majority of the flickering actually occurs at mid-level.
 
I think the way to implement it is to fade in/fade out the color of adjacent voxels based on the position of the object within each voxel so that it smoothly interpolates instead of jumping from 0 to 1.

 

I'm trying to re-attempt this but I just realised I don't actually know how to track how much each part of an object is within a voxel. Originally I had thought of accessing the geometry shader stage of my voxelization and storing the difference between the position of each voxel and triangle.

Then I set my input for alpha into the voxel texture as 1-density. But this doesn't help the flickering - it actually makes it worse because when my alpha value is set to one, it reduces the color bleeding of the entire scene. Thus it flickers between color bleeding and little color bleeding - leading to flashing.

Edited by gboxentertainment

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In my attempts of trying to reduce flickering I have come across an unusual discovery:

 

There is much less mid-level flickering in the z direction than there is in the x direction. i.e. Flickering caused by voxels at lod = 1 and lod = 2 is much less in the z direction (as opposed to lod = 0 (densest level), where there is the same amount of flickering no matter what direction).

 

Looking at the debug view I noticed that when I switch to lod = 1 debug, there seems to be much more information captured in the voxels in the x direction, than in the z direction:

 

[attachment=18352:gibox-debug0.jpg]

 

As you can notice in the above image, the voxels are a lot thicker on the facing surfaces of the left and right walls than on the wall at the very back.

 

Originally, a while ago when I had first discovered this, I had thought that this must be caused by some incorrect filtering during the mip-map stage. But I have checked my code many many times and voxels are filtered in exactly the same manner in each direction.

 

There must be something that I'm doing wrong during the mip-mapping stage which requires further investigation.

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So it turns out I had misinterpreted the original code that my method is based on. I am in fact manually mip-mapping to downsample my voxels.

#version 430

layout(local_size_x = 16, local_size_y = 8, local_size_z = 1) in;

layout(binding = 0, rgba8) uniform image3D srcMip;
layout(binding = 1, rgba8) uniform image3D dstMip;

uniform uint direction;

void main()
{
	ivec3 dstSize = imageSize(dstMip);

	if(gl_GlobalInvocationID.x >= dstSize.x || gl_GlobalInvocationID.y >= dstSize.y || gl_GlobalInvocationID.z >= dstSize.z){
		// out of range, ignore
	} else {
		ivec3 dstPos = ivec3(gl_GlobalInvocationID);
		ivec3 srcPos = dstPos*2;
		vec4 outColor;

		vec4 srcCol0 = imageLoad(srcMip, srcPos + ivec3(0,0,0));
		vec4 srcCol1 = imageLoad(srcMip, srcPos + ivec3(1,0,0));
		vec4 srcCol2 = imageLoad(srcMip, srcPos + ivec3(2,0,0));
		vec4 srcCol3 = imageLoad(srcMip, srcPos + ivec3(0,1,0));
		vec4 srcCol4 = imageLoad(srcMip, srcPos + ivec3(1,1,0));
		vec4 srcCol5 = imageLoad(srcMip, srcPos + ivec3(2,1,0));
		vec4 srcCol6 = imageLoad(srcMip, srcPos + ivec3(0,2,0));
		vec4 srcCol7 = imageLoad(srcMip, srcPos + ivec3(1,2,0));
		vec4 srcCol8 = imageLoad(srcMip, srcPos + ivec3(2,2,0));

		vec4 srcCol9 = imageLoad(srcMip, srcPos + ivec3(0,0,1));
		vec4 srcCol10 = imageLoad(srcMip, srcPos + ivec3(1,0,1));
		vec4 srcCol11 = imageLoad(srcMip, srcPos + ivec3(2,0,1));
		vec4 srcCol12 = imageLoad(srcMip, srcPos + ivec3(0,1,1));
		vec4 srcCol13 = imageLoad(srcMip, srcPos + ivec3(1,1,1));
		vec4 srcCol14 = imageLoad(srcMip, srcPos + ivec3(2,1,1));
		vec4 srcCol15 = imageLoad(srcMip, srcPos + ivec3(0,2,1));
		vec4 srcCol16 = imageLoad(srcMip, srcPos + ivec3(1,2,1));
		vec4 srcCol17 = imageLoad(srcMip, srcPos + ivec3(2,2,1));

		vec4 srcCol18 = imageLoad(srcMip, srcPos + ivec3(0,0,2));
		vec4 srcCol19 = imageLoad(srcMip, srcPos + ivec3(1,0,2));
		vec4 srcCol20 = imageLoad(srcMip, srcPos + ivec3(2,0,2));
		vec4 srcCol21 = imageLoad(srcMip, srcPos + ivec3(0,1,2));
		vec4 srcCol22 = imageLoad(srcMip, srcPos + ivec3(1,1,2));
		vec4 srcCol23 = imageLoad(srcMip, srcPos + ivec3(2,1,2));
		vec4 srcCol24 = imageLoad(srcMip, srcPos + ivec3(0,2,2));
		vec4 srcCol25 = imageLoad(srcMip, srcPos + ivec3(1,2,2));
		vec4 srcCol26 = imageLoad(srcMip, srcPos + ivec3(2,2,2));

	if(direction == 0) {
		//+X direction
		outColor.xyz = mix(srcCol0.xyz, srcCol1.xyz, 1.0 - srcCol0.w)
					+ mix(srcCol1.xyz, srcCol2.xyz, 1.0 - srcCol1.w)
					+ mix(srcCol3.xyz, srcCol4.xyz, 1.0 - srcCol3.w)
					+ mix(srcCol4.xyz, srcCol5.xyz, 1.0 - srcCol4.w)
					+ mix(srcCol6.xyz, srcCol7.xyz, 1.0 - srcCol6.w)
					+ mix(srcCol7.xyz, srcCol8.xyz, 1.0 - srcCol7.w)

					+ mix(srcCol9.xyz, srcCol10.xyz, 1.0 - srcCol9.w)
					+ mix(srcCol10.xyz, srcCol11.xyz, 1.0 - srcCol10.w)
					+ mix(srcCol12.xyz, srcCol13.xyz, 1.0 - srcCol12.w)
					+ mix(srcCol13.xyz, srcCol14.xyz, 1.0 - srcCol13.w)
					+ mix(srcCol15.xyz, srcCol16.xyz, 1.0 - srcCol15.w)
					+ mix(srcCol16.xyz, srcCol17.xyz, 1.0 - srcCol16.w)
					
					+ mix(srcCol18.xyz, srcCol19.xyz, 1.0 - srcCol18.w)
					+ mix(srcCol19.xyz, srcCol20.xyz, 1.0 - srcCol19.w)
					+ mix(srcCol21.xyz, srcCol22.xyz, 1.0 - srcCol21.w)
					+ mix(srcCol22.xyz, srcCol23.xyz, 1.0 - srcCol22.w)
					+ mix(srcCol24.xyz, srcCol25.xyz, 1.0 - srcCol24.w)
					+ mix(srcCol25.xyz, srcCol26.xyz, 1.0 - srcCol25.w);
		outColor.w = 4.0 - (1.0 - srcCol0.w) * (1.0 - srcCol1.w)
						- (1.0 - srcCol1.w) * (1.0 - srcCol2.w)
						- (1.0 - srcCol3.w) * (1.0 - srcCol4.w)
						- (1.0 - srcCol4.w) * (1.0 - srcCol5.w)
						- (1.0 - srcCol6.w) * (1.0 - srcCol7.w)
						- (1.0 - srcCol7.w) * (1.0 - srcCol8.w)
						
						- (1.0 - srcCol9.w) * (1.0 - srcCol10.w)
						- (1.0 - srcCol10.w) * (1.0 - srcCol11.w)
						- (1.0 - srcCol12.w) * (1.0 - srcCol13.w)
						- (1.0 - srcCol13.w) * (1.0 - srcCol14.w)
						- (1.0 - srcCol15.w) * (1.0 - srcCol16.w)
						- (1.0 - srcCol16.w) * (1.0 - srcCol17.w)
						
						- (1.0 - srcCol18.w) * (1.0 - srcCol19.w)
						- (1.0 - srcCol19.w) * (1.0 - srcCol20.w)
						- (1.0 - srcCol21.w) * (1.0 - srcCol22.w)
						- (1.0 - srcCol22.w) * (1.0 - srcCol23.w)
						- (1.0 - srcCol24.w) * (1.0 - srcCol25.w)
						- (1.0 - srcCol25.w) * (1.0 - srcCol26.w);

	} else if(direction == 1) {
		//-X direction
		outColor.xyz = mix(srcCol1.xyz, srcCol0.xyz, 1.0 - srcCol1.w)
					+ mix(srcCol2.xyz, srcCol1.xyz, 1.0 - srcCol2.w)
					+ mix(srcCol4.xyz, srcCol3.xyz, 1.0 - srcCol4.w)
					+ mix(srcCol5.xyz, srcCol4.xyz, 1.0 - srcCol5.w)
					+ mix(srcCol7.xyz, srcCol6.xyz, 1.0 - srcCol7.w)
					+ mix(srcCol8.xyz, srcCol7.xyz, 1.0 - srcCol8.w)

					+ mix(srcCol10.xyz, srcCol9.xyz, 1.0 - srcCol10.w)
					+ mix(srcCol11.xyz, srcCol10.xyz, 1.0 - srcCol11.w)
					+ mix(srcCol13.xyz, srcCol12.xyz, 1.0 - srcCol13.w)
					+ mix(srcCol14.xyz, srcCol13.xyz, 1.0 - srcCol14.w)
					+ mix(srcCol16.xyz, srcCol15.xyz, 1.0 - srcCol16.w)
					+ mix(srcCol17.xyz, srcCol16.xyz, 1.0 - srcCol17.w)
					
					+ mix(srcCol19.xyz, srcCol18.xyz, 1.0 - srcCol19.w)
					+ mix(srcCol20.xyz, srcCol19.xyz, 1.0 - srcCol20.w)
					+ mix(srcCol22.xyz, srcCol21.xyz, 1.0 - srcCol22.w)
					+ mix(srcCol23.xyz, srcCol22.xyz, 1.0 - srcCol23.w)
					+ mix(srcCol25.xyz, srcCol24.xyz, 1.0 - srcCol25.w)
					+ mix(srcCol26.xyz, srcCol25.xyz, 1.0 - srcCol26.w);
		outColor.w = 4.0 - (1.0 - srcCol1.w) * (1.0 - srcCol0.w)
						- (1.0 - srcCol2.w) * (1.0 - srcCol1.w)
						- (1.0 - srcCol4.w) * (1.0 - srcCol3.w)
						- (1.0 - srcCol5.w) * (1.0 - srcCol4.w)
						- (1.0 - srcCol7.w) * (1.0 - srcCol6.w)
						- (1.0 - srcCol8.w) * (1.0 - srcCol7.w)

						- (1.0 - srcCol10.w) * (1.0 - srcCol9.w)
						- (1.0 - srcCol11.w) * (1.0 - srcCol10.w)
						- (1.0 - srcCol13.w) * (1.0 - srcCol12.w)
						- (1.0 - srcCol14.w) * (1.0 - srcCol13.w)
						- (1.0 - srcCol16.w) * (1.0 - srcCol15.w)
						- (1.0 - srcCol17.w) * (1.0 - srcCol16.w)
						
						- (1.0 - srcCol19.w) * (1.0 - srcCol18.w)
						- (1.0 - srcCol20.w) * (1.0 - srcCol19.w)
						- (1.0 - srcCol22.w) * (1.0 - srcCol21.w)
						- (1.0 - srcCol23.w) * (1.0 - srcCol22.w)
						- (1.0 - srcCol25.w) * (1.0 - srcCol24.w)
						- (1.0 - srcCol26.w) * (1.0 - srcCol25.w);

	} else if(direction == 2) {
		//+Y direction
		outColor.xyz = mix(srcCol0.xyz, srcCol3.xyz, 1.0 - srcCol0.w)
					+ mix(srcCol3.xyz, srcCol6.xyz, 1.0 - srcCol3.w)
					+ mix(srcCol1.xyz, srcCol4.xyz, 1.0 - srcCol1.w)
					+ mix(srcCol4.xyz, srcCol7.xyz, 1.0 - srcCol4.w)
					+ mix(srcCol2.xyz, srcCol5.xyz, 1.0 - srcCol2.w)
					+ mix(srcCol5.xyz, srcCol8.xyz, 1.0 - srcCol5.w)

					+ mix(srcCol9.xyz, srcCol12.xyz, 1.0 - srcCol9.w)
					+ mix(srcCol12.xyz, srcCol15.xyz, 1.0 - srcCol12.w)
					+ mix(srcCol10.xyz, srcCol13.xyz, 1.0 - srcCol10.w)
					+ mix(srcCol13.xyz, srcCol16.xyz, 1.0 - srcCol13.w)
					+ mix(srcCol11.xyz, srcCol14.xyz, 1.0 - srcCol11.w)
					+ mix(srcCol14.xyz, srcCol17.xyz, 1.0 - srcCol14.w)
					
					+ mix(srcCol18.xyz, srcCol21.xyz, 1.0 - srcCol18.w)
					+ mix(srcCol21.xyz, srcCol24.xyz, 1.0 - srcCol21.w)
					+ mix(srcCol19.xyz, srcCol22.xyz, 1.0 - srcCol19.w)
					+ mix(srcCol22.xyz, srcCol25.xyz, 1.0 - srcCol22.w)
					+ mix(srcCol20.xyz, srcCol23.xyz, 1.0 - srcCol20.w)
					+ mix(srcCol23.xyz, srcCol26.xyz, 1.0 - srcCol23.w);
		outColor.w = 4.0 - (1.0 - srcCol0.w) * (1.0 - srcCol3.w)
						- (1.0 - srcCol3.w) * (1.0 - srcCol6.w)
						- (1.0 - srcCol1.w) * (1.0 - srcCol4.w)
						- (1.0 - srcCol4.w) * (1.0 - srcCol7.w)
						- (1.0 - srcCol2.w) * (1.0 - srcCol5.w)
						- (1.0 - srcCol5.w) * (1.0 - srcCol8.w)
						
						- (1.0 - srcCol9.w) * (1.0 - srcCol12.w)
						- (1.0 - srcCol12.w) * (1.0 - srcCol15.w)
						- (1.0 - srcCol10.w) * (1.0 - srcCol13.w)
						- (1.0 - srcCol13.w) * (1.0 - srcCol16.w)
						- (1.0 - srcCol11.w) * (1.0 - srcCol14.w)
						- (1.0 - srcCol14.w) * (1.0 - srcCol17.w)
						
						- (1.0 - srcCol18.w) * (1.0 - srcCol21.w)
						- (1.0 - srcCol21.w) * (1.0 - srcCol24.w)
						- (1.0 - srcCol19.w) * (1.0 - srcCol22.w)
						- (1.0 - srcCol22.w) * (1.0 - srcCol25.w)
						- (1.0 - srcCol20.w) * (1.0 - srcCol23.w)
						- (1.0 - srcCol23.w) * (1.0 - srcCol26.w);
	} 
	else if(direction == 3) {
		//-Y direction
		outColor.xyz = mix(srcCol3.xyz, srcCol0.xyz, 1.0 - srcCol3.w)
					+ mix(srcCol6.xyz, srcCol3.xyz, 1.0 - srcCol6.w)
					+ mix(srcCol4.xyz, srcCol1.xyz, 1.0 - srcCol4.w)
					+ mix(srcCol7.xyz, srcCol4.xyz, 1.0 - srcCol7.w)
					+ mix(srcCol5.xyz, srcCol2.xyz, 1.0 - srcCol5.w)
					+ mix(srcCol8.xyz, srcCol5.xyz, 1.0 - srcCol8.w)
					
					+ mix(srcCol15.xyz, srcCol12.xyz, 1.0 - srcCol15.w)
					+ mix(srcCol12.xyz, srcCol9.xyz, 1.0 - srcCol12.w)
					+ mix(srcCol16.xyz, srcCol13.xyz, 1.0 - srcCol16.w)
					+ mix(srcCol13.xyz, srcCol10.xyz, 1.0 - srcCol13.w)
					+ mix(srcCol17.xyz, srcCol14.xyz, 1.0 - srcCol17.w)
					+ mix(srcCol14.xyz, srcCol11.xyz, 1.0 - srcCol14.w)
					
					+ mix(srcCol24.xyz, srcCol21.xyz, 1.0 - srcCol24.w)
					+ mix(srcCol21.xyz, srcCol18.xyz, 1.0 - srcCol21.w)
					+ mix(srcCol25.xyz, srcCol22.xyz, 1.0 - srcCol25.w)
					+ mix(srcCol22.xyz, srcCol19.xyz, 1.0 - srcCol22.w)
					+ mix(srcCol26.xyz, srcCol23.xyz, 1.0 - srcCol26.w)
					+ mix(srcCol23.xyz, srcCol20.xyz, 1.0 - srcCol23.w);
		outColor.w = 4.0 - (1.0 - srcCol3.w) * (1.0 - srcCol0.w)
						- (1.0 - srcCol6.w) * (1.0 - srcCol3.w)
						- (1.0 - srcCol4.w) * (1.0 - srcCol1.w)
						- (1.0 - srcCol7.w) * (1.0 - srcCol4.w)
						- (1.0 - srcCol5.w) * (1.0 - srcCol2.w)
						- (1.0 - srcCol8.w) * (1.0 - srcCol5.w)
						
						- (1.0 - srcCol15.w) * (1.0 - srcCol12.w)
						- (1.0 - srcCol12.w) * (1.0 - srcCol9.w)
						- (1.0 - srcCol16.w) * (1.0 - srcCol13.w)
						- (1.0 - srcCol13.w) * (1.0 - srcCol10.w)
						- (1.0 - srcCol17.w) * (1.0 - srcCol14.w)
						- (1.0 - srcCol14.w) * (1.0 - srcCol11.w)
						
						- (1.0 - srcCol24.w) * (1.0 - srcCol21.w)
						- (1.0 - srcCol21.w) * (1.0 - srcCol18.w)
						- (1.0 - srcCol25.w) * (1.0 - srcCol22.w)
						- (1.0 - srcCol22.w) * (1.0 - srcCol19.w)
						- (1.0 - srcCol23.w) * (1.0 - srcCol23.w)
						- (1.0 - srcCol14.w) * (1.0 - srcCol20.w);
	} else if(direction == 4) {
		//+Z direction
		outColor.xyz = mix(srcCol0.xyz, srcCol9.xyz, 1.0 - srcCol0.w)
					+ mix(srcCol9.xyz, srcCol18.xyz, 1.0 - srcCol9.w)
					+ mix(srcCol1.xyz, srcCol10.xyz, 1.0 - srcCol1.w)
					+ mix(srcCol10.xyz, srcCol19.xyz, 1.0 - srcCol10.w)
					+ mix(srcCol2.xyz, srcCol11.xyz, 1.0 - srcCol2.w)
					+ mix(srcCol11.xyz, srcCol20.xyz, 1.0 - srcCol11.w)

					+ mix(srcCol3.xyz, srcCol12.xyz, 1.0 - srcCol3.w)
					+ mix(srcCol12.xyz, srcCol21.xyz, 1.0 - srcCol12.w)
					+ mix(srcCol4.xyz, srcCol13.xyz, 1.0 - srcCol14.w)
					+ mix(srcCol13.xyz, srcCol22.xyz, 1.0 - srcCol13.w)
					+ mix(srcCol5.xyz, srcCol14.xyz, 1.0 - srcCol5.w)
					+ mix(srcCol14.xyz, srcCol23.xyz, 1.0 - srcCol14.w)
					
					+ mix(srcCol6.xyz, srcCol15.xyz, 1.0 - srcCol6.w)
					+ mix(srcCol15.xyz, srcCol24.xyz, 1.0 - srcCol15.w)
					+ mix(srcCol7.xyz, srcCol16.xyz, 1.0 - srcCol7.w)
					+ mix(srcCol16.xyz, srcCol25.xyz, 1.0 - srcCol16.w)
					+ mix(srcCol8.xyz, srcCol17.xyz, 1.0 - srcCol8.w)
					+ mix(srcCol17.xyz, srcCol26.xyz, 1.0 - srcCol17.w);
		outColor.w = 4.0 - (1.0 - srcCol0.w) * (1.0 - srcCol9.w)
						- (1.0 - srcCol9.w) * (1.0 - srcCol18.w)
						- (1.0 - srcCol1.w) * (1.0 - srcCol10.w)
						- (1.0 - srcCol10.w) * (1.0 - srcCol19.w)
						- (1.0 - srcCol2.w) * (1.0 - srcCol11.w)
						- (1.0 - srcCol11.w) * (1.0 - srcCol20.w)
						
						- (1.0 - srcCol3.w) * (1.0 - srcCol12.w)
						- (1.0 - srcCol12.w) * (1.0 - srcCol21.w)
						- (1.0 - srcCol4.w) * (1.0 - srcCol13.w)
						- (1.0 - srcCol13.w) * (1.0 - srcCol22.w)
						- (1.0 - srcCol5.w) * (1.0 - srcCol14.w)
						- (1.0 - srcCol14.w) * (1.0 - srcCol23.w)
						
						- (1.0 - srcCol6.w) * (1.0 - srcCol15.w)
						- (1.0 - srcCol15.w) * (1.0 - srcCol24.w)
						- (1.0 - srcCol7.w) * (1.0 - srcCol6.w)
						- (1.0 - srcCol16.w) * (1.0 - srcCol25.w)
						- (1.0 - srcCol8.w) * (1.0 - srcCol17.w)
						- (1.0 - srcCol17.w) * (1.0 - srcCol26.w);
	} else if(direction == 5) {
		//-Z direction
		outColor.xyz = mix(srcCol9.xyz, srcCol0.xyz, 1.0 - srcCol9.w)
					+ mix(srcCol18.xyz, srcCol9.xyz, 1.0 - srcCol18.w)
					+ mix(srcCol10.xyz, srcCol1.xyz, 1.0 - srcCol10.w)
					+ mix(srcCol19.xyz, srcCol10.xyz, 1.0 - srcCol19.w)
					+ mix(srcCol11.xyz, srcCol2.xyz, 1.0 - srcCol11.w)
					+ mix(srcCol20.xyz, srcCol11.xyz, 1.0 - srcCol20.w)

					+ mix(srcCol12.xyz, srcCol3.xyz, 1.0 - srcCol12.w)
					+ mix(srcCol21.xyz, srcCol12.xyz, 1.0 - srcCol21.w)
					+ mix(srcCol13.xyz, srcCol4.xyz, 1.0 - srcCol13.w)
					+ mix(srcCol22.xyz, srcCol13.xyz, 1.0 - srcCol22.w)
					+ mix(srcCol14.xyz, srcCol5.xyz, 1.0 - srcCol14.w)
					+ mix(srcCol23.xyz, srcCol14.xyz, 1.0 - srcCol23.w)
					
					+ mix(srcCol15.xyz, srcCol6.xyz, 1.0 - srcCol15.w)
					+ mix(srcCol24.xyz, srcCol15.xyz, 1.0 - srcCol24.w)
					+ mix(srcCol16.xyz, srcCol7.xyz, 1.0 - srcCol16.w)
					+ mix(srcCol25.xyz, srcCol16.xyz, 1.0 - srcCol25.w)
					+ mix(srcCol17.xyz, srcCol8.xyz, 1.0 - srcCol17.w)
					+ mix(srcCol26.xyz, srcCol17.xyz, 1.0 - srcCol26.w);
		outColor.w = 4.0 - (1.0 - srcCol0.w) * (1.0 - srcCol9.w)
						- (1.0 - srcCol9.w) * (1.0 - srcCol18.w)
						- (1.0 - srcCol1.w) * (1.0 - srcCol10.w)
						- (1.0 - srcCol10.w) * (1.0 - srcCol19.w)
						- (1.0 - srcCol2.w) * (1.0 - srcCol11.w)
						- (1.0 - srcCol11.w) * (1.0 - srcCol20.w)
						
						- (1.0 - srcCol3.w) * (1.0 - srcCol12.w)
						- (1.0 - srcCol12.w) * (1.0 - srcCol21.w)
						- (1.0 - srcCol4.w) * (1.0 - srcCol13.w)
						- (1.0 - srcCol13.w) * (1.0 - srcCol22.w)
						- (1.0 - srcCol5.w) * (1.0 - srcCol14.w)
						- (1.0 - srcCol14.w) * (1.0 - srcCol23.w)
						
						- (1.0 - srcCol6.w) * (1.0 - srcCol15.w)
						- (1.0 - srcCol15.w) * (1.0 - srcCol24.w)
						- (1.0 - srcCol7.w) * (1.0 - srcCol6.w)
						- (1.0 - srcCol16.w) * (1.0 - srcCol25.w)
						- (1.0 - srcCol8.w) * (1.0 - srcCol17.w)
						- (1.0 - srcCol17.w) * (1.0 - srcCol26.w);
	}
	
		outColor.xyz *= 0.2;

		imageStore(dstMip, dstPos, outColor);
	}
}

However, I figured out that I have only been transferring my values in the -X direction! because in my shader code:

void TextureManager::mipMapPass(GLuint shader, GLuint tex, int dir, int voxDim)
{
	glUseProgram(shader);

	int workGroupSize[3] = {};
	glGetProgramiv(shader, GL_COMPUTE_WORK_GROUP_SIZE, workGroupSize);
	if (workGroupSize[0] * workGroupSize[1] * workGroupSize[2] == 0){
		cout << "failed to load compute shader" << endl;
		return;
	}

	int mipLevels = GetBitIndex(voxDim) + 1;
	for (int mip = 1; mip < mipLevels; mip++)
	{
		glUniform1ui(glGetUniformLocation(shader, "direction"), dir);

		glBindImageTexture(0, tex, mip - 1, GL_TRUE, 0, GL_READ_ONLY, GL_RGBA8);
		glBindImageTexture(1, tex, mip, GL_TRUE, 0, GL_WRITE_ONLY, GL_RGBA8);

		glDispatchCompute(
			((voxDim >> 1) + workGroupSize[0] - 1) / workGroupSize[0],
			((voxDim >> 1) + workGroupSize[1] - 1) / workGroupSize[1],
			((voxDim >> 1) + workGroupSize[2] - 1) / workGroupSize[2]);
	}
}

I only run this function once with dir = 0.

 

The issue that I'm facing now is when I run this function 6 times for each direction, it doesn't accumulate the values in each direction, instead overwriting the 3d texture with the last direction.

If I use hardware generation of mipmaps and then do the transfer of values to neighbouring voxels in each direction for each mip level, the results come out wrong.

Edited by gboxentertainment

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      PipelineStateDesc PSODesc; RasterizerStateDesc &RasterizerDesc = PSODesc.GraphicsPipeline.RasterizerDesc; RasterizerDesc.FillMode = FILL_MODE_SOLID; RasterizerDesc.CullMode = CULL_MODE_NONE; RasterizerDesc.FrontCounterClockwise = True; RasterizerDesc.ScissorEnable = True; RasterizerDesc.AntialiasedLineEnable = False; Depth-stencil and blend states are defined in a similar fashion.
      Another important thing that pipeline state object encompasses is the input layout description that defines how inputs to the vertex shader, which is the very first shader stage, should be read from the memory. Input layout may define several vertex streams that contain values of different formats and sizes:
      // Define input layout InputLayoutDesc &Layout = PSODesc.GraphicsPipeline.InputLayout; LayoutElement TextLayoutElems[] = {     LayoutElement( 0, 0, 3, VT_FLOAT32, False ),     LayoutElement( 1, 0, 4, VT_UINT8, True ),     LayoutElement( 2, 0, 2, VT_FLOAT32, False ), }; Layout.LayoutElements = TextLayoutElems; Layout.NumElements = _countof( TextLayoutElems ); Finally, pipeline state defines primitive topology type. When all required members are initialized, a pipeline state object can be created by IRenderDevice::CreatePipelineState() method:
      // Define shader and primitive topology PSODesc.GraphicsPipeline.PrimitiveTopologyType = PRIMITIVE_TOPOLOGY_TYPE_TRIANGLE; PSODesc.GraphicsPipeline.pVS = pVertexShader; PSODesc.GraphicsPipeline.pPS = pPixelShader; PSODesc.Name = "My pipeline state"; m_pDev->CreatePipelineState(PSODesc, &m_pPSO); When PSO object is bound to the pipeline, the engine invokes all API-specific commands to set all states specified by the object. In case of Direct3D12 this maps directly to setting the D3D12 PSO object. In case of Direct3D11, this involves setting individual state objects (such as rasterizer and blend states), shaders, input layout etc. In case of OpenGL, this requires a number of fine-grain state tweaking calls. Diligent Engine keeps track of currently bound states and only calls functions to update these states that have actually changed.
      Binding Shader Resources
      Direct3D11 and OpenGL utilize fine-grain resource binding models, where an application binds individual buffers and textures to certain shader or program resource binding slots. Direct3D12 uses a very different approach, where resource descriptors are grouped into tables, and an application can bind all resources in the table at once by setting the table in the command list. Resource binding model in Diligent Engine is designed to leverage this new method. It introduces a new object called shader resource binding that encapsulates all resource bindings required for all shaders in a certain pipeline state. It also introduces the classification of shader variables based on the frequency of expected change that helps the engine group them into tables under the hood:
      Static variables (SHADER_VARIABLE_TYPE_STATIC) are variables that are expected to be set only once. They may not be changed once a resource is bound to the variable. Such variables are intended to hold global constants such as camera attributes or global light attributes constant buffers. Mutable variables (SHADER_VARIABLE_TYPE_MUTABLE) define resources that are expected to change on a per-material frequency. Examples may include diffuse textures, normal maps etc. Dynamic variables (SHADER_VARIABLE_TYPE_DYNAMIC) are expected to change frequently and randomly. Shader variable type must be specified during shader creation by populating an array of ShaderVariableDesc structures and initializing ShaderCreationAttribs::Desc::VariableDesc and ShaderCreationAttribs::Desc::NumVariables members (see example of shader creation above).
      Static variables cannot be changed once a resource is bound to the variable. They are bound directly to the shader object. For instance, a shadow map texture is not expected to change after it is created, so it can be bound directly to the shader:
      PixelShader->GetShaderVariable( "g_tex2DShadowMap" )->Set( pShadowMapSRV ); Mutable and dynamic variables are bound via a new Shader Resource Binding object (SRB) that is created by the pipeline state (IPipelineState::CreateShaderResourceBinding()):
      m_pPSO->CreateShaderResourceBinding(&m_pSRB); Note that an SRB is only compatible with the pipeline state it was created from. SRB object inherits all static bindings from shaders in the pipeline, but is not allowed to change them.
      Mutable resources can only be set once for every instance of a shader resource binding. Such resources are intended to define specific material properties. For instance, a diffuse texture for a specific material is not expected to change once the material is defined and can be set right after the SRB object has been created:
      m_pSRB->GetVariable(SHADER_TYPE_PIXEL, "tex2DDiffuse")->Set(pDiffuseTexSRV); In some cases it is necessary to bind a new resource to a variable every time a draw command is invoked. Such variables should be labeled as dynamic, which will allow setting them multiple times through the same SRB object:
      m_pSRB->GetVariable(SHADER_TYPE_VERTEX, "cbRandomAttribs")->Set(pRandomAttrsCB); Under the hood, the engine pre-allocates descriptor tables for static and mutable resources when an SRB objcet is created. Space for dynamic resources is dynamically allocated at run time. Static and mutable resources are thus more efficient and should be used whenever possible.
      As you can see, Diligent Engine does not expose low-level details of how resources are bound to shader variables. One reason for this is that these details are very different for various APIs. The other reason is that using low-level binding methods is extremely error-prone: it is very easy to forget to bind some resource, or bind incorrect resource such as bind a buffer to the variable that is in fact a texture, especially during shader development when everything changes fast. Diligent Engine instead relies on shader reflection system to automatically query the list of all shader variables. Grouping variables based on three types mentioned above allows the engine to create optimized layout and take heavy lifting of matching resources to API-specific resource location, register or descriptor in the table.
      This post gives more details about the resource binding model in Diligent Engine.
      Setting the Pipeline State and Committing Shader Resources
      Before any draw or compute command can be invoked, the pipeline state needs to be bound to the context:
      m_pContext->SetPipelineState(m_pPSO); Under the hood, the engine sets the internal PSO object in the command list or calls all the required native API functions to properly configure all pipeline stages.
      The next step is to bind all required shader resources to the GPU pipeline, which is accomplished by IDeviceContext::CommitShaderResources() method:
      m_pContext->CommitShaderResources(m_pSRB, COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES); The method takes a pointer to the shader resource binding object and makes all resources the object holds available for the shaders. In the case of D3D12, this only requires setting appropriate descriptor tables in the command list. For older APIs, this typically requires setting all resources individually.
      Next-generation APIs require the application to track the state of every resource and explicitly inform the system about all state transitions. For instance, if a texture was used as render target before, while the next draw command is going to use it as shader resource, a transition barrier needs to be executed. Diligent Engine does the heavy lifting of state tracking.  When CommitShaderResources() method is called with COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES flag, the engine commits and transitions resources to correct states at the same time. Note that transitioning resources does introduce some overhead. The engine tracks state of every resource and it will not issue the barrier if the state is already correct. But checking resource state is an overhead that can sometimes be avoided. The engine provides IDeviceContext::TransitionShaderResources() method that only transitions resources:
      m_pContext->TransitionShaderResources(m_pPSO, m_pSRB); In some scenarios it is more efficient to transition resources once and then only commit them.
      Invoking Draw Command
      The final step is to set states that are not part of the PSO, such as render targets, vertex and index buffers. Diligent Engine uses Direct3D11-syle API that is translated to other native API calls under the hood:
      ITextureView *pRTVs[] = {m_pRTV}; m_pContext->SetRenderTargets(_countof( pRTVs ), pRTVs, m_pDSV); // Clear render target and depth buffer const float zero[4] = {0, 0, 0, 0}; m_pContext->ClearRenderTarget(nullptr, zero); m_pContext->ClearDepthStencil(nullptr, CLEAR_DEPTH_FLAG, 1.f); // Set vertex and index buffers IBuffer *buffer[] = {m_pVertexBuffer}; Uint32 offsets[] = {0}; Uint32 strides[] = {sizeof(MyVertex)}; m_pContext->SetVertexBuffers(0, 1, buffer, strides, offsets, SET_VERTEX_BUFFERS_FLAG_RESET); m_pContext->SetIndexBuffer(m_pIndexBuffer, 0); Different native APIs use various set of function to execute draw commands depending on command details (if the command is indexed, instanced or both, what offsets in the source buffers are used etc.). For instance, there are 5 draw commands in Direct3D11 and more than 9 commands in OpenGL with something like glDrawElementsInstancedBaseVertexBaseInstance not uncommon. Diligent Engine hides all details with single IDeviceContext::Draw() method that takes takes DrawAttribs structure as an argument. The structure members define all attributes required to perform the command (primitive topology, number of vertices or indices, if draw call is indexed or not, if draw call is instanced or not, if draw call is indirect or not, etc.). For example:
      DrawAttribs attrs; attrs.IsIndexed = true; attrs.IndexType = VT_UINT16; attrs.NumIndices = 36; attrs.Topology = PRIMITIVE_TOPOLOGY_TRIANGLE_LIST; pContext->Draw(attrs); For compute commands, there is IDeviceContext::DispatchCompute() method that takes DispatchComputeAttribs structure that defines compute grid dimension.
      Source Code
      Full engine source code is available on GitHub and is free to use. The repository contains two samples, asteroids performance benchmark and example Unity project that uses Diligent Engine in native plugin.
      AntTweakBar sample is Diligent Engine’s “Hello World” example.

       
      Atmospheric scattering sample is a more advanced example. It demonstrates how Diligent Engine can be used to implement various rendering tasks: loading textures from files, using complex shaders, rendering to multiple render targets, using compute shaders and unordered access views, etc.

      Asteroids performance benchmark is based on this demo developed by Intel. It renders 50,000 unique textured asteroids and allows comparing performance of Direct3D11 and Direct3D12 implementations. Every asteroid is a combination of one of 1000 unique meshes and one of 10 unique textures.

      Finally, there is an example project that shows how Diligent Engine can be integrated with Unity.

      Future Work
      The engine is under active development. It currently supports Windows desktop, Universal Windows and Android platforms. Direct3D11, Direct3D12, OpenGL/GLES backends are now feature complete. Vulkan backend is coming next, and support for more platforms is planned.
    • By reenigne
      For those that don't know me. I am the individual who's two videos are listed here under setup for https://wiki.libsdl.org/Tutorials
      I also run grhmedia.com where I host the projects and code for the tutorials I have online.
      Recently, I received a notice from youtube they will be implementing their new policy in protecting video content as of which I won't be monetized till I meat there required number of viewers and views each month.

      Frankly, I'm pretty sick of youtube. I put up a video and someone else learns from it and puts up another video and because of the way youtube does their placement they end up with more views.
      Even guys that clearly post false information such as one individual who said GLEW 2.0 was broken because he didn't know how to compile it. He in short didn't know how to modify the script he used because he didn't understand make files and how the requirements of the compiler and library changes needed some different flags.

      At the end of the month when they implement this I will take down the content and host on my own server purely and it will be a paid system and or patreon. 

      I get my videos may be a bit dry, I generally figure people are there to learn how to do something and I rather not waste their time. 
      I used to also help people for free even those coming from the other videos. That won't be the case any more. I used to just take anyone emails and work with them my email is posted on the site.

      I don't expect to get the required number of subscribers in that time or increased views. Even if I did well it wouldn't take care of each reoccurring month.
      I figure this is simpler and I don't plan on putting some sort of exorbitant fee for a monthly subscription or the like.
      I was thinking on the lines of a few dollars 1,2, and 3 and the larger subscription gets you assistance with the content in the tutorials if needed that month.
      Maybe another fee if it is related but not directly in the content. 
      The fees would serve to cut down on the number of people who ask for help and maybe encourage some of the people to actually pay attention to what is said rather than do their own thing. That actually turns out to be 90% of the issues. I spent 6 hours helping one individual last week I must have asked him 20 times did you do exactly like I said in the video even pointed directly to the section. When he finally sent me a copy of the what he entered I knew then and there he had not. I circled it and I pointed out that wasn't what I said to do in the video. I didn't tell him what was wrong and how I knew that way he would go back and actually follow what it said to do. He then reported it worked. Yea, no kidding following directions works. But hey isn't alone and well its part of the learning process.

      So the point of this isn't to be a gripe session. I'm just looking for a bit of feed back. Do you think the fees are unreasonable?
      Should I keep the youtube channel and do just the fees with patreon or do you think locking the content to my site and require a subscription is an idea.

      I'm just looking at the fact it is unrealistic to think youtube/google will actually get stuff right or that youtube viewers will actually bother to start looking for more accurate videos. 
    • By Balma Alparisi
      i got error 1282 in my code.
      sf::ContextSettings settings; settings.majorVersion = 4; settings.minorVersion = 5; settings.attributeFlags = settings.Core; sf::Window window; window.create(sf::VideoMode(1600, 900), "Texture Unit Rectangle", sf::Style::Close, settings); window.setActive(true); window.setVerticalSyncEnabled(true); glewInit(); GLuint shaderProgram = createShaderProgram("FX/Rectangle.vss", "FX/Rectangle.fss"); float vertex[] = { -0.5f,0.5f,0.0f, 0.0f,0.0f, -0.5f,-0.5f,0.0f, 0.0f,1.0f, 0.5f,0.5f,0.0f, 1.0f,0.0f, 0.5,-0.5f,0.0f, 1.0f,1.0f, }; GLuint indices[] = { 0,1,2, 1,2,3, }; GLuint vao; glGenVertexArrays(1, &vao); glBindVertexArray(vao); GLuint vbo; glGenBuffers(1, &vbo); glBindBuffer(GL_ARRAY_BUFFER, vbo); glBufferData(GL_ARRAY_BUFFER, sizeof(vertex), vertex, GL_STATIC_DRAW); GLuint ebo; glGenBuffers(1, &ebo); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices,GL_STATIC_DRAW); glVertexAttribPointer(0, 3, GL_FLOAT, false, sizeof(float) * 5, (void*)0); glEnableVertexAttribArray(0); glVertexAttribPointer(1, 2, GL_FLOAT, false, sizeof(float) * 5, (void*)(sizeof(float) * 3)); glEnableVertexAttribArray(1); GLuint texture[2]; glGenTextures(2, texture); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture[0]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); sf::Image* imageOne = new sf::Image; bool isImageOneLoaded = imageOne->loadFromFile("Texture/container.jpg"); if (isImageOneLoaded) { glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, imageOne->getSize().x, imageOne->getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageOne->getPixelsPtr()); glGenerateMipmap(GL_TEXTURE_2D); } delete imageOne; glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, texture[1]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); sf::Image* imageTwo = new sf::Image; bool isImageTwoLoaded = imageTwo->loadFromFile("Texture/awesomeface.png"); if (isImageTwoLoaded) { glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, imageTwo->getSize().x, imageTwo->getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageTwo->getPixelsPtr()); glGenerateMipmap(GL_TEXTURE_2D); } delete imageTwo; glUniform1i(glGetUniformLocation(shaderProgram, "inTextureOne"), 0); glUniform1i(glGetUniformLocation(shaderProgram, "inTextureTwo"), 1); GLenum error = glGetError(); std::cout << error << std::endl; sf::Event event; bool isRunning = true; while (isRunning) { while (window.pollEvent(event)) { if (event.type == event.Closed) { isRunning = false; } } glClear(GL_COLOR_BUFFER_BIT); if (isImageOneLoaded && isImageTwoLoaded) { glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture[0]); glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, texture[1]); glUseProgram(shaderProgram); } glBindVertexArray(vao); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr); glBindVertexArray(0); window.display(); } glDeleteVertexArrays(1, &vao); glDeleteBuffers(1, &vbo); glDeleteBuffers(1, &ebo); glDeleteProgram(shaderProgram); glDeleteTextures(2,texture); return 0; } and this is the vertex shader
      #version 450 core layout(location=0) in vec3 inPos; layout(location=1) in vec2 inTexCoord; out vec2 TexCoord; void main() { gl_Position=vec4(inPos,1.0); TexCoord=inTexCoord; } and the fragment shader
      #version 450 core in vec2 TexCoord; uniform sampler2D inTextureOne; uniform sampler2D inTextureTwo; out vec4 FragmentColor; void main() { FragmentColor=mix(texture(inTextureOne,TexCoord),texture(inTextureTwo,TexCoord),0.2); } I was expecting awesomeface.png on top of container.jpg

    • By khawk
      We've just released all of the source code for the NeHe OpenGL lessons on our Github page at https://github.com/gamedev-net/nehe-opengl. code - 43 total platforms, configurations, and languages are included.
      Now operated by GameDev.net, NeHe is located at http://nehe.gamedev.net where it has been a valuable resource for developers wanting to learn OpenGL and graphics programming.

      View full story
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