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• By racarate
Hey everybody!
I am trying to replicate all these cool on-screen debug visuals I see in all the SIGGRAPH and GDC talks, but I really don't know where to start.  The only resource I know of is almost 16 years old:
http://number-none.com/product/Interactive Profiling, Part 1/index.html
Does anybody have a more up-to-date reference?  Do people use minimal UI libraries like Dear ImgGui?  Also, If I am profiling OpenGL ES 3.0 (which doesn't have timer queries) is there really anything I can do to measure performance GPU-wise?  Or should I just chart CPU-side frame time?  I feel like this is something people re-invent for every game there has gotta be a tutorial out there... right?

• By Achivai
Hey, I am semi-new to 3d-programming and I've hit a snag. I have one object, let's call it Object A. This object has a long int array of 3d xyz-positions stored in it's vbo as an instanced attribute. I am using these numbers to instance object A a couple of thousand times. So far so good.
Now I've hit a point where I want to remove one of these instances of object A while the game is running, but I'm not quite sure how to go about it. At first my thought was to update the instanced attribute of Object A and change the positions to some dummy number that I could catch in the vertex shader and then decide there whether to draw the instance of Object A or not, but I think that would be expensive to do while the game is running, considering that it might have to be done several times every frame in some cases.
I'm not sure how to proceed, anyone have any tips?
• By fleissi
Hey guys!

I'm new here and I recently started developing my own rendering engine. It's open source, based on OpenGL/DirectX and C++.
The full source code is hosted on github:
https://github.com/fleissna/flyEngine

I would appreciate if people with experience in game development / engine desgin could take a look at my source code. I'm looking for honest, constructive criticism on how to improve the engine.
I'm currently writing my master's thesis in computer science and in the recent year I've gone through all the basics about graphics programming, learned DirectX and OpenGL, read some articles on Nvidia GPU Gems, read books and integrated some of this stuff step by step into the engine.

I know about the basics, but I feel like there is some missing link that I didn't get yet to merge all those little pieces together.

Features I have so far:
- Dynamic shader generation based on material properties
- Dynamic sorting of meshes to be renderd based on shader and material
- Rendering large amounts of static meshes
- Hierarchical culling (detail + view frustum)
- Limited support for dynamic (i.e. moving) meshes
- Normal, Parallax and Relief Mapping implementations
- Wind animations based on vertex displacement
- A very basic integration of the Bullet physics engine
- Procedural Grass generation
- Some post processing effects (Depth of Field, Light Volumes, Screen Space Reflections, God Rays)
- Caching mechanisms for textures, shaders, materials and meshes

Features I would like to have:
- Global illumination methods
- Scalable physics
- Occlusion culling
- A nice procedural terrain generator
- Scripting
- Level Editing
- Sound system
- Optimization techniques

Books I have so far:
- Real-Time Rendering Third Edition
- 3D Game Programming with DirectX 11
- Vulkan Cookbook (not started yet)

I hope you guys can take a look at my source code and if you're really motivated, feel free to contribute :-)
There are some videos on youtube that demonstrate some of the features:
Procedural grass on the GPU
Procedural Terrain Engine
Quadtree detail and view frustum culling

The long term goal is to turn this into a commercial game engine. I'm aware that this is a very ambitious goal, but I'm sure it's possible if you work hard for it.

Bye,

Phil
• By tj8146
I have attached my project in a .zip file if you wish to run it for yourself.
I am making a simple 2d top-down game and I am trying to run my code to see if my window creation is working and to see if my timer is also working with it. Every time I run it though I get errors. And when I fix those errors, more come, then the same errors keep appearing. I end up just going round in circles.  Is there anyone who could help with this?

Errors when I build my code:
1>Renderer.cpp 1>c:\users\documents\opengl\game\game\renderer.h(15): error C2039: 'string': is not a member of 'std' 1>c:\program files (x86)\windows kits\10\include\10.0.16299.0\ucrt\stddef.h(18): note: see declaration of 'std' 1>c:\users\documents\opengl\game\game\renderer.h(15): error C2061: syntax error: identifier 'string' 1>c:\users\documents\opengl\game\game\renderer.cpp(28): error C2511: 'bool Game::Rendering::initialize(int,int,bool,std::string)': overloaded member function not found in 'Game::Rendering' 1>c:\users\documents\opengl\game\game\renderer.h(9): note: see declaration of 'Game::Rendering' 1>c:\users\documents\opengl\game\game\renderer.cpp(35): error C2597: illegal reference to non-static member 'Game::Rendering::window' 1>c:\users\documents\opengl\game\game\renderer.cpp(36): error C2597: illegal reference to non-static member 'Game::Rendering::window' 1>c:\users\documents\opengl\game\game\renderer.cpp(43): error C2597: illegal reference to non-static member 'Game::Rendering::window' 1>Done building project "Game.vcxproj" -- FAILED. ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Renderer.cpp
#include <GL/glew.h> #include <GLFW/glfw3.h> #include "Renderer.h" #include "Timer.h" #include <iostream> namespace Game { GLFWwindow* window; /* Initialize the library */ Rendering::Rendering() { mClock = new Clock; } Rendering::~Rendering() { shutdown(); } bool Rendering::initialize(uint width, uint height, bool fullscreen, std::string window_title) { if (!glfwInit()) { return -1; } /* Create a windowed mode window and its OpenGL context */ window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL); if (!window) { glfwTerminate(); return -1; } /* Make the window's context current */ glfwMakeContextCurrent(window); glViewport(0, 0, (GLsizei)width, (GLsizei)height); glOrtho(0, (GLsizei)width, (GLsizei)height, 0, 1, -1); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glfwSwapInterval(1); glEnable(GL_SMOOTH); glEnable(GL_DEPTH_TEST); glEnable(GL_BLEND); glDepthFunc(GL_LEQUAL); glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); glEnable(GL_TEXTURE_2D); glLoadIdentity(); return true; } bool Rendering::render() { /* Loop until the user closes the window */ if (!glfwWindowShouldClose(window)) return false; /* Render here */ mClock->reset(); glfwPollEvents(); if (mClock->step()) { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glfwSwapBuffers(window); mClock->update(); } return true; } void Rendering::shutdown() { glfwDestroyWindow(window); glfwTerminate(); } GLFWwindow* Rendering::getCurrentWindow() { return window; } } Renderer.h
#pragma once namespace Game { class Clock; class Rendering { public: Rendering(); ~Rendering(); bool initialize(uint width, uint height, bool fullscreen, std::string window_title = "Rendering window"); void shutdown(); bool render(); GLFWwindow* getCurrentWindow(); private: GLFWwindow * window; Clock* mClock; }; } Timer.cpp
#include <GL/glew.h> #include <GLFW/glfw3.h> #include <time.h> #include "Timer.h" namespace Game { Clock::Clock() : mTicksPerSecond(50), mSkipTics(1000 / mTicksPerSecond), mMaxFrameSkip(10), mLoops(0) { mLastTick = tick(); } Clock::~Clock() { } bool Clock::step() { if (tick() > mLastTick && mLoops < mMaxFrameSkip) return true; return false; } void Clock::reset() { mLoops = 0; } void Clock::update() { mLastTick += mSkipTics; mLoops++; } clock_t Clock::tick() { return clock(); } } TImer.h
#pragma once #include "Common.h" namespace Game { class Clock { public: Clock(); ~Clock(); void update(); bool step(); void reset(); clock_t tick(); private: uint mTicksPerSecond; ufloat mSkipTics; uint mMaxFrameSkip; uint mLoops; uint mLastTick; }; } Common.h
#pragma once #include <cstdio> #include <cstdlib> #include <ctime> #include <cstring> #include <cmath> #include <iostream> namespace Game { typedef unsigned char uchar; typedef unsigned short ushort; typedef unsigned int uint; typedef unsigned long ulong; typedef float ufloat; }
Game.zip
• By lxjk
Hi guys,
There are many ways to do light culling in tile-based shading. I've been playing with this idea for a while, and just want to throw it out there.
Because tile frustums are general small compared to light radius, I tried using cone test to reduce false positives introduced by commonly used sphere-frustum test.
On top of that, I use distance to camera rather than depth for near/far test (aka. sliced by spheres).
This method can be naturally extended to clustered light culling as well.
The following image shows the general ideas

Performance-wise I get around 15% improvement over sphere-frustum test. You can also see how a single light performs as the following: from left to right (1) standard rendering of a point light; then tiles passed the test of (2) sphere-frustum test; (3) cone test; (4) spherical-sliced cone test

I put the details in my blog post (https://lxjk.github.io/2018/03/25/Improve-Tile-based-Light-Culling-with-Spherical-sliced-Cone.html), GLSL source code included!

Eric

# OpenGL Heightmap collision detection?

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## Recommended Posts

Hi all! I have recently started to learn OpenGL and its been great so far due to the vast resources available online. However I am stuck when it came to rendering heightmaps. Basically, I have a camera class and also a working terrain loader/renderer in the code. I can render the heightmap from a raw file fine and also move my model as 3rd person around the heightmap. However, I noticed that sometimes my char goes through the hills and that is not that ideal. My terrain renderer (from nehe) have a function to return the height of the heightmap at a given x and y coordinates. I have so far tried a simple height difference test between subject and heightmap height output but I noticed that the movements are very "choppy". It just don't look natural at all. Also sometimes the character will still go into the hills and cause the whole program to crash out. I am wondering if anyone could give some advice/examples to remedy this problem. I would like to say that I am not an expert programmer so please be gentle with me :D I can include my code if needed ( /code works here?) Thanks all and I hope someone can help me out.

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You'll probably want to do real triangle collision instead of just heightmap look-ups.

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Quote:
 Original post by polymorphedYou'll probably want to do real triangle collision instead of just heightmap look-ups.Google for "triangle sphere collision"

Hi !

Thanks for the reply! However I noticed that the methods used are for sphere/epsiloid to an even plane. Technically I am not testing vs. a plane but rather a point (points could vary every pixel due to the heightmap's resolution etc). This causes a "stutter" in the detection and hence makes my character looks as though it's bouncing up and down at a fast speed.

I am wondering if there is any way to fix this? I have not tried the more complicated solution but I have tried sphere/plane and ray intersection. I used the height value (y) of the map as char.x and char.z as a reference plane.

here is my pseudo code if anyone is kind enough to have a look through :P
void RenderScene() {	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);		glLoadIdentity();					CheckAndComputeInputs();//left these few lines in in case I did something wrong	model.heading.x = cos(90-model.direction);	model.heading.z = sin(90-model.direction);	Camera.x += ((View.x + Heading.x * -6) - Camera.x) / 3;	Camera.y += ((View.y + Heading.y * -6 + 1) - Camera.y) / 3; 	Camera.z += ((View.z + Heading.z * -6) - Camera.z) / 3;		model.position.x+=model.speed.x;	model.position.z+=model.speed.z;		View.x = model.position.x;	View.y = model.position.y + 1;	View.z = model.position.z;	model.speed.x /= airdrag;	model.speed.y /= airdrag;	model.speed.z /= airdrag;			gluLookAt(Camera.x, Camera.y, Camera.z, // the position 	View.x, View.y, View.z, //the View	0.0f,1.0f,0.0f); //the Up-Vector	// I am trying to average the points around the character	float a = (float)Height(g_HeightMap, (int)model.position.x, (int)model.position.z);	float b = (float)Height(g_HeightMap, (int)model.position.x+0.05, (int)model.position.z+0.05);	float c = (float)Height(g_HeightMap, (int)model.position.x-0.05, (int)model.position.z-0.05);	float d = (float)Height(g_HeightMap, (int)model.position.x+0.05, (int)model.position.z);	float e = (float)Height(g_HeightMap, (int)model.position.x, (int)model.position.z+0.05);	float f = (float)Height(g_HeightMap, (int)model.position.x-0.05, (int)model.position.z);	float g = (float)Height(g_HeightMap, (int)model.position.x, (int)model.position.z-0.05);	float ave = (a+b+c+d+e+f+g)/7;	if (model.position.y &lt; ave+2)	{		float newPos = ave+2 ;		model.position.y = newPos;	}	if (model.position.y &gt; ave+5)	{		float newPos = ave + 5;		model.position.y = newPos;	}	glPushMatrix();	StencilShadow();	DrawGround();	MoreStencilShadow();	// these is the "shadow"	// left a good chunk in	glTranslatef(model.position.x, model.position.y, model.position.z);	glScalef(0.04f,0.04f,0.04f);	glRotatef(model.direction*180/PI -110,0.0,1.0,0.0);	g_Model.DrawModel();	glDisable(GL_CULL_FACE);	glEnable(GL_TEXTURE_2D);	glEnable(GL_DEPTH_TEST);	glDisable(GL_BLEND);	glEnable(GL_LIGHTING);	glPopMatrix();	// end of draw shadow	glDisable(GL_STENCIL_TEST);	// Here I draw the character	glPushMatrix();	glEnable(GL_TEXTURE_2D);	glEnable(GL_CULL_FACE); // Turn back face culling on	glCullFace(GL_FRONT);		glTranslatef(model.position.x, model.position.y, model.position.z);	glScalef(0.04f,0.04f,0.04f);	glRotatef(model.direction*180/PI -110,0.0,1.0,0.0);	glColor3ub(255, 255, 255);	g_Model.DrawModel();	glDisable(GL_CULL_FACE);	glDisable(GL_TEXTURE_2D);	glPopMatrix();	SwapBuffers(g_hDC);}

[Edited by - jonathanc on March 31, 2008 9:54:36 PM]

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Quote:
 Original post by jonathancI have recently started to learn OpenGL and its been great so far due to the vast resources available online.
Take care, most of those resources are badly out of date, with only a few exceptions.
Quote:
 Original post by jonathancI have so far tried a simple height difference test between subject and heightmap height output but I noticed that the movements are very "choppy". It just don't look natural at all. Also sometimes the character will still go into the hills and cause the whole program to crash out.
This has nothing to do with GL, it's an indicator you're probably overrunning some array or stuff like this. Try using small heightmaps such as 4x4 and think at the various reads/writes, this will probably give you an hint on where the error could be.
Also, _ASSERTE(_CrtCheckMemory()) is your friend. Drop in a few of them.
Quote:
 Original post by polymorphedYou'll probably want to do real triangle collision instead of just heightmap look-ups.
Not really. Heightmaps are 2D entities and such, heightmap lookups are sufficient when properly implemented. Assuming he's not perturbing the heightmap with high-frequency signals, the triangles are just linear interpolations of a function of the heightmap value, as such, increasing the processing data won't give out much.

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@Krohm

Thanks for the advice :D And yes there are a lot of contradicting opinions out there. I have read up a bit on the sphere/plane collision etc but I feel that I do not need to go that detail for this app. I just want to render a char moving on my heightmap without going into the terrain. I will see what I can do :D

by the way, did you look at my code snippet ? It's the Renderscene func which is the core of it all at the moment. I couldn't find anything wrong at the moment but maybe you could spot a mistake or two.

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You should try something like this.
This is quite the same as you did, but with some poundering (? sorry I'm french and my english's not always what I'd like it to be) (weighting's the right word ?) each vertex. Looking at your code, if your player jumps I can understand that's because you have no weighting of your position versus how far you are from each point, so when you change coords then the average just change.

// I am trying to average the points around the characterint ModelPosX = (int)model.position.x;int ModelPosZ = (int)model.position.z;float h00 = (float)Height(g_HeightMap, ModelPosX, ModelPosZ);float h10 = (float)Height(g_HeightMap, ModelPosX+1, ModelPosZ);float h01 = (float)Height(g_HeightMap, ModelPosX, ModelPosZ+1);float h11 = (float)Height(g_HeightMap, ModelPosX+1, ModelPosZ+1);float FracModelPosX = model.position.x - ModelPosX;float FracModelPosZ = model.position.z - ModelPosZ;float ave = h00*(1.0f-FracModelPosX)*(1.0f-FracModelPosZ) + h10*FracModelPosX*(1.0f-FracModelPosZ) + h01*(1.0f-FracModelPosX)*FracModelPosZ + h11*FracModelPosX*FracModelPosZ;// so if i'm near X.Z, then result is h00, near X+1.Z > h10, X.Z+1 > h01, X+1.Z+1 > h11;// if i'm half way between h00 and h10; FracPosX = 0.5 FracPosZ = 0, result is 0.5*h00 + 0.5*h10, seem to be ok.model.position.y = ave;// optional : average Y over time, warning this is heavy frame-rate dependant// model.position.y = (model.position.y * 4.0f + ave)/5.0f;//float ave = (a+b+c+d+e+f+g)/7;/* // no need for this ?if (model.position.y < ave+2){float newPos = ave+2 ;model.position.y = newPos;}if (model.position.y > ave+5){float newPos = ave + 5;model.position.y = newPos;}*/

I personnally use some triangle detection using heights, but if you're just starting that may be complex because it depends on how the triangles are rendered (ask and i'll paste some of my old my code, but i'll leave it to you to interpret it :)).

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Quote:
 Original post by KaeltykYou should try something like this.This is quite the same as you did, but with some poundering (? sorry I'm french and my english's not always what I'd like it to be) (weighting's the right word ?) each vertex. Looking at your code, if your player jumps I can understand that's because you have no weighting of your position versus how far you are from each point, so when you change coords then the average just change.*** Source Snippet Removed ***I personnally use some triangle detection using heights, but if you're just starting that may be complex because it depends on how the triangles are rendered (ask and i'll paste some of my old my code, but i'll leave it to you to interpret it :)).

Thanks a lot Kaeltyk! Your suggestion worked brilliantly! :D I will try the second bit once I optimise the rest of my code a bit. It just feels so great when your code finally turns out to be something awesome on the screen.

To be honest , I am using a height map loader code from a source I have found online and it isn't mine. However, I understand how it works though because it's pretty straight forward and simple.

Thanks a lot again and yes, I would be interested at looking at your code if it is possible (at looking at, hmmm...my english isn't that good either :P) [cpp] a [/cpp]

[Edited by - jonathanc on March 31, 2008 9:44:49 PM]

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You're welcome, I've gone throught these computations before :).

Now to explain a bit more, the above code is exact only when your quad is flat. But this is usually not the case as we render triangles and a heightmap with different heigths for each corner of the quads.

example of when it's not visually accurate :
h00 = 0; h01 = 0; h10 = 0; h11 = 10; player at center.
The average given by the formula in the center is 2.5, which is ok from the average point of view. But as we rendered the quad as triangles, it is not the height of the visual the player is on.
Either the triangles were rendered (h00-h01-h10 then h10-h01-h11) then the player should be at height = 0.0 (he is on the h10-h01 edge), or the triangles are rendered (h00-h01-h11 then h11-h10-h01) and the player should be at height 0.5 (he is on the h00-h11 edge).

The following code works when you render triangles in the h00-h01-h10 order (and looking at the NeHe code this is not your case if you used the height map tutorial code)

rough code extracted from my old engine:
void CMap::PutObjectOnGround(CObject* Obj){	// Lookup for Object Cell 	// Cell X-Y have coordinates that are X-TableXSize/2.f, Y-TableYSize/2.f to same+1	float fX = Obj->Location.X + TableXSize/2.f;	float fY = Obj->Location.Y + TableYSize/2.f;	int X = (int)fX;	int Y = (int)fY;	float ZHeight = 0.f;	if ( X>=0 && X<TableXSize-1 && Y>=0 && Y<TableYSize-1 )	{		float XFrac = fX - X;		float YFrac = fY - Y;		if ( XFrac + YFrac < 1 )		{	// We're on Left triangle (X,Y) (X+1,Y) (X,Y+1) of the tile			// Plane z = ax + by + c			// x=0 y=0 > c = Cellheight[X.Y] 			// x=1 y=0 > a+c = CellHeight[X+1.Y] > a = Cellheight[X+1/Y] - c;			// x=0 y=1 > b+c = CellHeight[X.Y+1] > b = CellHeight[X.Y+1] - c			float c = CellHeights[(int)X+(int)Y*TableXSize];			float a = CellHeights[(int)X+1+(int)Y*TableXSize] - c;			float b = CellHeights[(int)X+(int)(Y+1)*TableXSize] - c;			ZHeight = XFrac * a + YFrac * b + c;		}		else		{	// We're on Right triangle (X+1,Y) (X+1,Y+1) (X,Y+1) of the tile			// Plane z = ax + by + c			// x=1 y=0 > a + c = Cellheight[X+1.Y]			// x=1 y=1 > a+b+c = CellHeight[X+1.Y+1]			// x=0 y=1 > b+c = CellHeight[X.Y+1]			// > b = CellHeight[X+1.Y+1] - Cellheight[X+1.Y];			// > c = CellHeight[X.Y+1] - b;			// > a = Cellheight[X+1.Y] - c;			float b = CellHeights[(int)X+1+(int)(Y+1)*TableXSize] - CellHeights[(int)X+1+(int)Y*TableXSize];			float c = CellHeights[(int)X+(int)(Y+1)*TableXSize] - b;			float a = CellHeights[(int)X+1+(int)Y*TableXSize] - c;			ZHeight = XFrac * a + YFrac * b + c;		}		Obj->Location.Z = Obj->Height + ZHeight*CELLHEIGHT;//		CellTable[(int)X+(int)Y*TableXSize].CellColor[0] = 1.f;	}	else	{		Obj->Location.Z = Obj->Height;	}}

Overall you need to check which triangle you're on, and solve the Height = a*FracX + b*FracY + c equation, knowing that
h00 = c (because FracX=0 and FracY=0)
h10 = a+c (because FracX=1 and FracY=0)
h01 = b+c (because FracX=0 and FracY=1)
h11 = a+b+c (because FracX=1 and FracY=1)
and use only 3 of the above statements that match the triangle you're on.

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Hmm, I heard its something to do with the shadowmatrix plane but I have tried changing the plane[4] = (0,1,0,0) to 0,2,0,0 etc but it seems that plane[4] takes 1s and 0s only.

[Edited by - jonathanc on April 2, 2008 11:41:58 AM]