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Niruz

OpenGL
Tiled Deferred Frustum Culling issues

6 posts in this topic

I'm having some issues getting culling to work for the near/far plane per tile when doing tiled deferred shading. The way to do it in DirectX based on http://malegebi.wordpress.com/2012/01/30/a-new-era-of-forward-shading-is-coming/ is to do it like this.

    // Work out scale/bias from [0, 1]
    float2 tileScale = float2(DisplaySize.xy) * rcp(2.0f * float2(LightTileSize, LightTileSize));
    float2 tileBias = tileScale - float2(GroupID.xy);

    // Now work out composite projection matrix
    // Relevant matrix columns for this tile frusta
    float4 c1 = float4(Projection._11 * tileScale.x, 0.0f, tileBias.x, 0.0f);
    float4 c2 = float4(0.0f, -Projection._22 * tileScale.y, tileBias.y, 0.0f);
    float4 c4 = float4(0.0f, 0.0f, 1.0f, 0.0f);

    // Derive frustum planes
    float4 frustumPlanes[6];

    // Sides
    frustumPlanes[0] = c4 - c1;
    frustumPlanes[1] = c4 + c1;
    frustumPlanes[2] = c4 - c2;
    frustumPlanes[3] = c4 + c2;

    // Near/far
    frustumPlanes[4] = float4(0.0f, 0.0f,  1.0f, -minTileZ);
    frustumPlanes[5] = float4(0.0f, 0.0f, -1.0f,  maxTileZ);

I've tried just doing an opengl version of that but it doesn't seem to work, here's what I have so far, notice that near/far aren't correct:

vec4 frustumPlanes[6];

	vec2 tileScale = vec2(SCREEN_WIDTH,SCREEN_HEIGHT) * (1.0f / float( 2 * MAX_WORK_GROUP_SIZE));

	vec2 tileBias = tileScale - vec2(gl_WorkGroupID.xy);

	vec4 col1 = vec4(-projectionMatrix[0][0]  * tileScale.x, projectionMatrix[0][1], tileBias.x, projectionMatrix[0][3]); 

    vec4 col2 = vec4(projectionMatrix[1][0], -projectionMatrix[1][1] * tileScale.y, tileBias.y, projectionMatrix[1][3]);

    vec4 col4 = vec4(projectionMatrix[3][0], projectionMatrix[3][1],  -1.0f, projectionMatrix[3][3]); 

	//Left plane
    frustumPlanes[0] = col4 + col1;

    //right plane
    frustumPlanes[1] = col4 - col1;

    //top plane
    frustumPlanes[2] = col4 - col2;

    //bottom plane
    frustumPlanes[3] = col4 + col2;

    //near
    frustumPlanes[4] = vec4(0.0f, 0.0f, -1.0f,  -minDepthZ);

    //far
    frustumPlanes[5] = vec4(0.0f, 0.0f, -1.0f,  maxDepthZ);

	for(int i = 0; i < 4; i++)
    {
        frustumPlanes[i] *= 1.0f / length(frustumPlanes[i].xyz);
    }

I want to do near = vec4(0.0f, 0,0f, -1,0f, -minDepthZ) and for the far I want to do vec4(0.0f,0.0f,1.0f,maxDepthZ) which is like the directX version only reversed, I've been basing things on this link too http://www.lighthouse3d.com/tutorials/view-frustum-culling/clip-space-approach-extracting-the-planes/

 

But I cannot seem to get it to work, does anyone have any idea on how to correctly implement the near and far plane for the frustum?

Edited by Niruz
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I've tried reworking the code based on the AMD implementation, this is what I have now instead, only now the frustum for the tiles seems to have "flipped" or become reversed, the old implementation was based on directX which may have lead to some troubles, here's what I have now:

	vec4 frustumEqn[4];
    uint pxm = MAX_WORK_GROUP_SIZE * gl_WorkGroupID.x;
    uint pym = MAX_WORK_GROUP_SIZE * gl_WorkGroupID.y;
    uint pxp = MAX_WORK_GROUP_SIZE * (gl_WorkGroupID.x + 1);
    uint pyp = MAX_WORK_GROUP_SIZE * (gl_WorkGroupID.y + 1);

    uint uWindowWidthEvenlyDivisibleByTileRes = MAX_WORK_GROUP_SIZE * GetNumTilesX();
    uint uWindowHeightEvenlyDivisibleByTileRes = MAX_WORK_GROUP_SIZE * GetNumTilesY();

    vec4 frustum[4];
    frustum[0] = ConvertProjToView( vec4( pxm / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, (uWindowHeightEvenlyDivisibleByTileRes - pym) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f, 1.0f, 1.0f) );
    frustum[1] = ConvertProjToView( vec4( pxp / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, (uWindowHeightEvenlyDivisibleByTileRes - pym) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f, 1.0f, 1.0f) );
    frustum[2] = ConvertProjToView( vec4( pxp / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, (uWindowHeightEvenlyDivisibleByTileRes - pyp) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f, 1.0f ,1.0f) );
    frustum[3] = ConvertProjToView( vec4( pxm / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, (uWindowHeightEvenlyDivisibleByTileRes - pyp) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f, 1.0f, 1.0f) );

    for (int i = 0; i < 4; i++)
        frustumEqn[i] = CreatePlaneEquation(frustum[i],frustum[(i+1) & 3]);

    barrier();

    int threadsPerTile = MAX_WORK_GROUP_SIZE * MAX_WORK_GROUP_SIZE;

    for (uint i = 0; i < NUM_OF_LIGHTS; i+= threadsPerTile)
    {
        uint il = gl_LocalInvocationIndex + i;

        if (il < NUM_OF_LIGHTS)
        {
            PointLight p = pointLights[il];

            vec4 viewPos = viewMatrix * vec4(p.posX,p.posY,p.posZ, 1.0f);
            float r = p.radius;

            if (viewPos.z + minDepthZ < r && viewPos.z - maxDepthZ < r)
            {

            if( ( GetSignedDistanceFromPlane( viewPos, frustumEqn[0] ) < r ) &&
                ( GetSignedDistanceFromPlane( viewPos, frustumEqn[1] ) < r ) &&
                ( GetSignedDistanceFromPlane( viewPos, frustumEqn[2] ) < r ) &&
                ( GetSignedDistanceFromPlane( viewPos, frustumEqn[3] ) < r) )

                {
                    uint id = atomicAdd(pointLightCount, 1);
                    pointLightIndex[id] = il;
                }
            }

        }
    }

And the functions used

vec3 ReconstructWP(float z, vec2 uv_f)
{
    vec4 sPos = vec4(uv_f * 2.0 - 1.0, z, 1.0);
    sPos = inverseViewProjectionMatrix * sPos;

    return (sPos.xyz / sPos.w);
}

vec4 ConvertProjToView( vec4 p )
{
    p = inverseProjectionMatrix * p;
    p /= p.w;
    return p;
}

// calculate the number of tiles in the horizontal direction
uint GetNumTilesX()
{
    return uint(( ( 1280 + MAX_WORK_GROUP_SIZE - 1 ) / float(MAX_WORK_GROUP_SIZE) ));
}

// calculate the number of tiles in the vertical direction
uint GetNumTilesY()
{
    return uint(( ( 720 + MAX_WORK_GROUP_SIZE - 1 ) / float(MAX_WORK_GROUP_SIZE) ));
}


vec4 CreatePlaneEquation( vec4 b, vec4 c )
{
    vec4 n;

    // normalize(cross( b.xyz-a.xyz, c.xyz-a.xyz )), except we know "a" is the origin
     n.xyz = normalize(cross( b.xyz, c.xyz ));

    // -(n dot a), except we know "a" is the origin
    n.w = 0;

    return n;
}

float GetSignedDistanceFromPlane( vec4 p, vec4 eqn )
{
    // dot( eqn.xyz, p.xyz ) + eqn.w, , except we know eqn.w is zero 
    // (see CreatePlaneEquation above)
    return dot( eqn.xyz, p.xyz );
}

Now, here's the funny part, in the picture below all tiles affected by a light are rendered in red, and if I move around it looks exactly like the world has somehow flipped everything, now I'm not sure how that could happen, but maybe someone has some ideas? 

Edited by Niruz
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I should probably add this maybe, this is the complete DirectX version from AMD used for tiled forward shading

//--------------------------------------------------------------------------------------
// File: ForwardPlus11.hlsl
//
// HLSL file for the ForwardPlus11 sample. Tiled light culling.
// 
// Author: Jason Stewart
// 
// Copyright © AMD Corporation. All rights reserved.
//--------------------------------------------------------------------------------------


#include "ForwardPlus11Common.hlsl"

#define FLT_MAX         3.402823466e+38F

//-----------------------------------------------------------------------------------------
// Textures and Buffers
//-----------------------------------------------------------------------------------------
Buffer<float4> g_PointLightBufferCenterAndRadius : register( t0 );
Buffer<float4> g_SpotLightBufferCenterAndRadius : register( t1 );

#if ( USE_DEPTH_CULLING == 1 )   // non-MSAA
Texture2D<float> g_DepthTexture : register( t2 );
#elif ( USE_DEPTH_CULLING == 2 ) // MSAA
Texture2DMS<float> g_DepthTexture : register( t2 );
#endif

RWBuffer<uint> g_PerTileLightIndexBufferOut : register( u0 );

//-----------------------------------------------------------------------------------------
// Group Shared Memory (aka local data share, or LDS)
//-----------------------------------------------------------------------------------------
#if ( USE_DEPTH_CULLING == 1 || USE_DEPTH_CULLING == 2 )
groupshared uint ldsZMax;
groupshared uint ldsZMin;
#endif

groupshared uint ldsLightIdxCounter;
groupshared uint ldsLightIdx[MAX_NUM_LIGHTS_PER_TILE];

//-----------------------------------------------------------------------------------------
// Helper functions
//-----------------------------------------------------------------------------------------

// this creates the standard Hessian-normal-form plane equation from three points, 
// except it is simplified for the case where the first point is the origin
float4 CreatePlaneEquation( float4 b, float4 c )
{
    float4 n;

    // normalize(cross( b.xyz-a.xyz, c.xyz-a.xyz )), except we know "a" is the origin
    n.xyz = normalize(cross( b.xyz, c.xyz ));

    // -(n dot a), except we know "a" is the origin
    n.w = 0;

    return n;
}

// point-plane distance, simplified for the case where 
// the plane passes through the origin
float GetSignedDistanceFromPlane( float4 p, float4 eqn )
{
    // dot( eqn.xyz, p.xyz ) + eqn.w, , except we know eqn.w is zero 
    // (see CreatePlaneEquation above)
    return dot( eqn.xyz, p.xyz );
}

// calculate the number of tiles in the horizontal direction
uint GetNumTilesX()
{
    return (uint)( ( g_uWindowWidth + TILE_RES - 1 ) / (float)TILE_RES );
}

// calculate the number of tiles in the vertical direction
uint GetNumTilesY()
{
    return (uint)( ( g_uWindowHeight + TILE_RES - 1 ) / (float)TILE_RES );
}

// convert a point from post-projection space into view space
float4 ConvertProjToView( float4 p )
{
    p = mul( p, g_mProjectionInv );
    p /= p.w;
    return p;
}

// convert a depth value from post-projection space into view space
float ConvertProjDepthToView( float z )
{
    z = 1.f / (z*g_mProjectionInv._34 + g_mProjectionInv._44);
    return z;
}

#if ( USE_DEPTH_CULLING == 1 || USE_DEPTH_CULLING == 2 )
void CalculateMinMaxDepthInLds( uint3 globalThreadIdx, uint depthBufferSampleIdx )
{
#if ( USE_DEPTH_CULLING == 1 )   // non-MSAA
    float depth = g_DepthTexture.Load( uint3(globalThreadIdx.x,globalThreadIdx.y,0) ).x;
#elif ( USE_DEPTH_CULLING == 2 ) // MSAA
    float depth = g_DepthTexture.Load( uint2(globalThreadIdx.x,globalThreadIdx.y), depthBufferSampleIdx ).x;
#endif
    float viewPosZ = ConvertProjDepthToView( depth );
    uint z = asuint( viewPosZ );
    if( depth != 0.f )
    {
        InterlockedMax( ldsZMax, z );
        InterlockedMin( ldsZMin, z );
    }
}
#endif

//-----------------------------------------------------------------------------------------
// Parameters for the light culling shader
//-----------------------------------------------------------------------------------------
#define NUM_THREADS_X TILE_RES
#define NUM_THREADS_Y TILE_RES
#define NUM_THREADS_PER_TILE (NUM_THREADS_X*NUM_THREADS_Y)

//-----------------------------------------------------------------------------------------
// Light culling shader
//-----------------------------------------------------------------------------------------
[numthreads(NUM_THREADS_X, NUM_THREADS_Y, 1)]
void CullLightsCS( uint3 globalIdx : SV_DispatchThreadID, uint3 localIdx : SV_GroupThreadID, uint3 groupIdx : SV_GroupID )
{
    uint localIdxFlattened = localIdx.x + localIdx.y*NUM_THREADS_X;
    uint tileIdxFlattened = groupIdx.x + groupIdx.y*GetNumTilesX();

    if( localIdxFlattened == 0 )
    {
#if ( USE_DEPTH_CULLING == 1 || USE_DEPTH_CULLING == 2 )
        ldsZMin = 0xffffffff;
        ldsZMax = 0;
#endif
        ldsLightIdxCounter = 0;
    }

    float4 frustumEqn[4];
    {   // construct frustum for this tile
        uint pxm = TILE_RES*groupIdx.x;
        uint pym = TILE_RES*groupIdx.y;
        uint pxp = TILE_RES*(groupIdx.x+1);
        uint pyp = TILE_RES*(groupIdx.y+1);

        uint uWindowWidthEvenlyDivisibleByTileRes = TILE_RES*GetNumTilesX();
        uint uWindowHeightEvenlyDivisibleByTileRes = TILE_RES*GetNumTilesY();

        // four corners of the tile, clockwise from top-left
        float4 frustum[4];
        frustum[0] = ConvertProjToView( float4( pxm/(float)uWindowWidthEvenlyDivisibleByTileRes*2.f-1.f, (uWindowHeightEvenlyDivisibleByTileRes-pym)/(float)uWindowHeightEvenlyDivisibleByTileRes*2.f-1.f,1.f,1.f) );
        frustum[1] = ConvertProjToView( float4( pxp/(float)uWindowWidthEvenlyDivisibleByTileRes*2.f-1.f, (uWindowHeightEvenlyDivisibleByTileRes-pym)/(float)uWindowHeightEvenlyDivisibleByTileRes*2.f-1.f,1.f,1.f) );
        frustum[2] = ConvertProjToView( float4( pxp/(float)uWindowWidthEvenlyDivisibleByTileRes*2.f-1.f, (uWindowHeightEvenlyDivisibleByTileRes-pyp)/(float)uWindowHeightEvenlyDivisibleByTileRes*2.f-1.f,1.f,1.f) );
        frustum[3] = ConvertProjToView( float4( pxm/(float)uWindowWidthEvenlyDivisibleByTileRes*2.f-1.f, (uWindowHeightEvenlyDivisibleByTileRes-pyp)/(float)uWindowHeightEvenlyDivisibleByTileRes*2.f-1.f,1.f,1.f) );

        // create plane equations for the four sides of the frustum, 
        // with the positive half-space outside the frustum (and remember, 
        // view space is left handed, so use the left-hand rule to determine 
        // cross product direction)
        for(uint i=0; i<4; i++)
            frustumEqn[i] = CreatePlaneEquation( frustum[i], frustum[(i+1)&3] );
    }

    GroupMemoryBarrierWithGroupSync();

    // calculate the min and max depth for this tile, 
    // to form the front and back of the frustum

#if ( USE_DEPTH_CULLING == 1 || USE_DEPTH_CULLING == 2 )
    float minZ = FLT_MAX;
    float maxZ = 0.f;

#if ( USE_DEPTH_CULLING == 1 )   // non-MSAA
    CalculateMinMaxDepthInLds( globalIdx, 0 );
#elif ( USE_DEPTH_CULLING == 2 ) // MSAA
    uint depthBufferWidth, depthBufferHeight, depthBufferNumSamples;
    g_DepthTexture.GetDimensions( depthBufferWidth, depthBufferHeight, depthBufferNumSamples );
    for( uint sampleIdx=0; sampleIdx<depthBufferNumSamples; sampleIdx++ )
    {
        CalculateMinMaxDepthInLds( globalIdx, sampleIdx );
    }
#endif

    GroupMemoryBarrierWithGroupSync();
    maxZ = asfloat( ldsZMax );
    minZ = asfloat( ldsZMin );
#endif

    // loop over the lights and do a sphere vs. frustum intersection test
    uint uNumPointLights = g_uNumLights & 0xFFFFu;
    for(uint i=0; i<uNumPointLights; i+=NUM_THREADS_PER_TILE)
    {
        uint il = localIdxFlattened + i;
        if( il < uNumPointLights )
        {
            float4 center = g_PointLightBufferCenterAndRadius[il];
            float r = center.w;
            center.xyz = mul( float4(center.xyz, 1), g_mWorldView ).xyz;

            // test if sphere is intersecting or inside frustum
#if ( USE_DEPTH_CULLING != 0 )
            if( -center.z + minZ < r && center.z - maxZ < r )
#else
            if( -center.z < r )
#endif
            {
                if( ( GetSignedDistanceFromPlane( center, frustumEqn[0] ) < r ) &&
                    ( GetSignedDistanceFromPlane( center, frustumEqn[1] ) < r ) &&
                    ( GetSignedDistanceFromPlane( center, frustumEqn[2] ) < r ) &&
                    ( GetSignedDistanceFromPlane( center, frustumEqn[3] ) < r ) )
                {
                    // do a thread-safe increment of the list counter 
                    // and put the index of this light into the list
                    uint dstIdx = 0;
                    InterlockedAdd( ldsLightIdxCounter, 1, dstIdx );
                    ldsLightIdx[dstIdx] = il;
                }
            }
        }
    }

    GroupMemoryBarrierWithGroupSync();

    // and again for spot lights
    uint uNumPointLightsInThisTile = ldsLightIdxCounter;
    uint uNumSpotLights = (g_uNumLights & 0xFFFF0000u) >> 16;
    for(uint j=0; j<uNumSpotLights; j+=NUM_THREADS_PER_TILE)
    {
        uint jl = localIdxFlattened + j;
        if( jl < uNumSpotLights )
        {
            float4 center = g_SpotLightBufferCenterAndRadius[jl];
            float r = center.w;
            center.xyz = mul( float4(center.xyz, 1), g_mWorldView ).xyz;

            // test if sphere is intersecting or inside frustum
#if ( USE_DEPTH_CULLING != 0 )
            if( -center.z + minZ < r && center.z - maxZ < r )
#else
            if( -center.z < r )
#endif
            {
                if( ( GetSignedDistanceFromPlane( center, frustumEqn[0] ) < r ) &&
                    ( GetSignedDistanceFromPlane( center, frustumEqn[1] ) < r ) &&
                    ( GetSignedDistanceFromPlane( center, frustumEqn[2] ) < r ) &&
                    ( GetSignedDistanceFromPlane( center, frustumEqn[3] ) < r ) )
                {
                    // do a thread-safe increment of the list counter 
                    // and put the index of this light into the list
                    uint dstIdx = 0;
                    InterlockedAdd( ldsLightIdxCounter, 1, dstIdx );
                    ldsLightIdx[dstIdx] = jl;
                }
            }
        }
    }

    GroupMemoryBarrierWithGroupSync();

    {   // write back
        uint startOffset = g_uMaxNumLightsPerTile*tileIdxFlattened;

        for(uint i=localIdxFlattened; i<uNumPointLightsInThisTile; i+=NUM_THREADS_PER_TILE)
        {
            // per-tile list of light indices
            g_PerTileLightIndexBufferOut[startOffset+i] = ldsLightIdx[i];
        }

        for(uint j=(localIdxFlattened+uNumPointLightsInThisTile); j<ldsLightIdxCounter; j+=NUM_THREADS_PER_TILE)
        {
            // per-tile list of light indices
            g_PerTileLightIndexBufferOut[startOffset+j+1] = ldsLightIdx[j];
        }

        if( localIdxFlattened == 0 )
        {
            // mark the end of each per-tile list with a sentinel (point lights)
            g_PerTileLightIndexBufferOut[startOffset+uNumPointLightsInThisTile] = LIGHT_INDEX_BUFFER_SENTINEL;

            // mark the end of each per-tile list with a sentinel (spot lights)
            g_PerTileLightIndexBufferOut[startOffset+ldsLightIdxCounter+1] = LIGHT_INDEX_BUFFER_SENTINEL;
        }
    }
}
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looks conceptually correctly to me, that's doing the flip from 2d top-down to 3d bottom-up coordinates:

 
frustum[0] = ConvertProjToView( float4( pxm/(float)uWindowWidthEvenlyDivisibleByTileRes*2.f-1.f, (uWindowHeightEvenlyDivisibleByTileRes-pym)/(float)uWindowHeightEvenlyDivisibleByTileRes*2.f-1.f,1.f,1.f) );
frustum[1] = ConvertProjToView( float4( pxp/(float)uWindowWidthEvenlyDivisibleByTileRes*2.f-1.f, (uWindowHeightEvenlyDivisibleByTileRes-pym)/(float)uWindowHeightEvenlyDivisibleByTileRes*2.f-1.f,1.f,1.f) );
frustum[2] = ConvertProjToView( float4( pxp/(float)uWindowWidthEvenlyDivisibleByTileRes*2.f-1.f, (uWindowHeightEvenlyDivisibleByTileRes-pyp)/(float)uWindowHeightEvenlyDivisibleByTileRes*2.f-1.f,1.f,1.f) );
frustum[3] = ConvertProjToView( float4( pxm/(float)uWindowWidthEvenlyDivisibleByTileRes*2.f-1.f, (uWindowHeightEvenlyDivisibleByTileRes-pyp)/(float)uWindowHeightEvenlyDivisibleByTileRes*2.f-1.f,1.f,1.f) );

 

maybe your debug output is buggy? :)

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Hmm, the way I output the tiles affected by a light is just with

if(pointLightCount >= 1)
{
	imageStore(finalImage, pixelPos, vec4(1.0f, 0.0f, 0.0f, 1.0f));
}

the pointLightCount variable being per tile, also I tried multiplying the y component of the frustums by -1 which puts the light in the correct position but that solution feels a bit hacky...

 frustum[0] = ConvertProjToView( vec4( pxm / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, -1.0f*((uWindowHeightEvenlyDivisibleByTileRes - pym) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f), 1.0f, 1.0f) );
    frustum[1] = ConvertProjToView( vec4( pxp / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, -1.0f*((uWindowHeightEvenlyDivisibleByTileRes - pym) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f), 1.0f, 1.0f) );
    frustum[2] = ConvertProjToView( vec4( pxp / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, -1.0f*((uWindowHeightEvenlyDivisibleByTileRes - pyp) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f), 1.0f ,1.0f) );
    frustum[3] = ConvertProjToView( vec4( pxm / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, -1.0f*((uWindowHeightEvenlyDivisibleByTileRes - pyp) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f), 1.0f, 1.0f) );

I mean it works as intended but I'm starting to think maybe my projection matrix is wrong, but then normal rendering shouldn't be working either

Edited by Niruz
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      Hello, I have been working on SH Irradiance map rendering, and I have been using a GLSL pixel shader to render SH irradiance to 2D irradiance maps for my static objects. I already have it working with 9 3D textures so far for the first 9 SH functions.
      In my GLSL shader, I have to send in 9 SH Coefficient 3D Texures that use RGBA8 as a pixel format. RGB being used for the coefficients for red, green, and blue, and the A for checking if the voxel is in use (for the 3D texture solidification shader to prevent bleeding).
      My problem is, I want to knock this number of textures down to something like 4 or 5. Getting even lower would be a godsend. This is because I eventually plan on adding more SH Coefficient 3D Textures for other parts of the game map (such as inside rooms, as opposed to the outside), to circumvent irradiance probe bleeding between rooms separated by walls. I don't want to reach the 32 texture limit too soon. Also, I figure that it would be a LOT faster.
      Is there a way I could, say, store 2 sets of SH Coefficients for 2 SH functions inside a texture with RGBA16 pixels? If so, how would I extract them from inside GLSL? Let me know if you have any suggestions ^^.
    • By KarimIO
      EDIT: I thought this was restricted to Attribute-Created GL contexts, but it isn't, so I rewrote the post.
      Hey guys, whenever I call SwapBuffers(hDC), I get a crash, and I get a "Too many posts were made to a semaphore." from Windows as I call SwapBuffers. What could be the cause of this?
      Update: No crash occurs if I don't draw, just clear and swap.
      static PIXELFORMATDESCRIPTOR pfd = // pfd Tells Windows How We Want Things To Be { sizeof(PIXELFORMATDESCRIPTOR), // Size Of This Pixel Format Descriptor 1, // Version Number PFD_DRAW_TO_WINDOW | // Format Must Support Window PFD_SUPPORT_OPENGL | // Format Must Support OpenGL PFD_DOUBLEBUFFER, // Must Support Double Buffering PFD_TYPE_RGBA, // Request An RGBA Format 32, // Select Our Color Depth 0, 0, 0, 0, 0, 0, // Color Bits Ignored 0, // No Alpha Buffer 0, // Shift Bit Ignored 0, // No Accumulation Buffer 0, 0, 0, 0, // Accumulation Bits Ignored 24, // 24Bit Z-Buffer (Depth Buffer) 0, // No Stencil Buffer 0, // No Auxiliary Buffer PFD_MAIN_PLANE, // Main Drawing Layer 0, // Reserved 0, 0, 0 // Layer Masks Ignored }; if (!(hDC = GetDC(windowHandle))) return false; unsigned int PixelFormat; if (!(PixelFormat = ChoosePixelFormat(hDC, &pfd))) return false; if (!SetPixelFormat(hDC, PixelFormat, &pfd)) return false; hRC = wglCreateContext(hDC); if (!hRC) { std::cout << "wglCreateContext Failed!\n"; return false; } if (wglMakeCurrent(hDC, hRC) == NULL) { std::cout << "Make Context Current Second Failed!\n"; return false; } ... // OGL Buffer Initialization glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT); glBindVertexArray(vao); glUseProgram(myprogram); glDrawElements(GL_TRIANGLES, indexCount, GL_UNSIGNED_SHORT, (void *)indexStart); SwapBuffers(GetDC(window_handle));  
    • By Tchom
      Hey devs!
       
      I've been working on a OpenGL ES 2.0 android engine and I have begun implementing some simple (point) lighting. I had something fairly simple working, so I tried to get fancy and added color-tinting light. And it works great... with only one or two lights. Any more than that, the application drops about 15 frames per light added (my ideal is at least 4 or 5). I know implementing lighting is expensive, I just didn't think it was that expensive. I'm fairly new to the world of OpenGL and GLSL, so there is a good chance I've written some crappy shader code. If anyone had any feedback or tips on how I can optimize this code, please let me know.
       
      Vertex Shader
      uniform mat4 u_MVPMatrix; uniform mat4 u_MVMatrix; attribute vec4 a_Position; attribute vec3 a_Normal; attribute vec2 a_TexCoordinate; varying vec3 v_Position; varying vec3 v_Normal; varying vec2 v_TexCoordinate; void main() { v_Position = vec3(u_MVMatrix * a_Position); v_TexCoordinate = a_TexCoordinate; v_Normal = vec3(u_MVMatrix * vec4(a_Normal, 0.0)); gl_Position = u_MVPMatrix * a_Position; } Fragment Shader
      precision mediump float; uniform vec4 u_LightPos["+numLights+"]; uniform vec4 u_LightColours["+numLights+"]; uniform float u_LightPower["+numLights+"]; uniform sampler2D u_Texture; varying vec3 v_Position; varying vec3 v_Normal; varying vec2 v_TexCoordinate; void main() { gl_FragColor = (texture2D(u_Texture, v_TexCoordinate)); float diffuse = 0.0; vec4 colourSum = vec4(1.0); for (int i = 0; i < "+numLights+"; i++) { vec3 toPointLight = vec3(u_LightPos[i]); float distance = length(toPointLight - v_Position); vec3 lightVector = normalize(toPointLight - v_Position); float diffuseDiff = 0.0; // The diffuse difference contributed from current light diffuseDiff = max(dot(v_Normal, lightVector), 0.0); diffuseDiff = diffuseDiff * (1.0 / (1.0 + ((1.0-u_LightPower[i])* distance * distance))); //Determine attenuatio diffuse += diffuseDiff; gl_FragColor.rgb *= vec3(1.0) / ((vec3(1.0) + ((vec3(1.0) - vec3(u_LightColours[i]))*diffuseDiff))); //The expensive part } diffuse += 0.1; //Add ambient light gl_FragColor.rgb *= diffuse; } Am I making any rookie mistakes? Or am I just being unrealistic about what I can do? Thanks in advance
    • By yahiko00
      Hi,
      Not sure to post at the right place, if not, please forgive me...
      For a game project I am working on, I would like to implement a 2D starfield as a background.
      I do not want to deal with static tiles, since I plan to slowly animate the starfield. So, I am trying to figure out how to generate a random starfield for the entire map.
      I feel that using a uniform distribution for the stars will not do the trick. Instead I would like something similar to the screenshot below, taken from the game Star Wars: Empire At War (all credits to Lucasfilm, Disney, and so on...).

      Is there someone who could have an idea of a distribution which could result in such a starfield?
      Any insight would be appreciated
    • By afraidofdark
      I have just noticed that, in quake 3 and half - life, dynamic models are effected from light map. For example in dark areas, gun that player holds seems darker. How did they achieve this effect ? I can use image based lighting techniques however (Like placing an environment probe and using it for reflections and ambient lighting), this tech wasn't used in games back then, so there must be a simpler method to do this.
      Here is a link that shows how modern engines does it. Indirect Lighting Cache It would be nice if you know a paper that explains this technique. Can I apply this to quake 3' s light map generator and bsp format ?
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