Get rid of the separate occupancy texture, use irradiance alpha channel.

Author: Adnn

src/apps/ch11_voxel/ch11_voxel/FrameGraph.cpp

@@ -215,8 +215,6 @@ void FrameGraph::renderFinalScene(const scenic::SceneTree & aSceneTree,
 
     glBindTextureUnit(6, mShadowMap);
     graphics::setUniform(program, "u_ShadowMap", 6);
-    glBindTextureUnit(10, aVoxelizer.mOccupancy);
-    graphics::setUniform(program, "u_VoxelsAlbedoTexture", 10);
     glBindTextureUnit(11, aVoxelizer.mIrradiance);
     graphics::setUniform(program, "u_VoxelsIrradianceTexture", 11);
 
@@ -239,8 +237,6 @@ void FrameGraph::renderConeTrace(const scenic::SceneTree & aSceneTree,
                                  Voxelizer & aVoxelizer, GLuint aMode)
 {
     const auto & program = mPrograms.mConeTrace;
-    glBindTextureUnit(10, aVoxelizer.mOccupancy);
-    graphics::setUniform(program, "u_VoxelsAlbedoTexture", 10);
     glBindTextureUnit(11, aVoxelizer.mIrradiance);
     graphics::setUniform(program, "u_VoxelsIrradianceTexture", 11);
     graphics::setUniform(program, "u_VoxelSize", aVoxelizer.mVoxelSize);

src/apps/ch11_voxel/ch11_voxel/Voxelization.cpp

@@ -347,60 +347,6 @@ void Voxelizer::voxelizeView(const scenic::SceneTree & aScene, GLuint aGridDimen
 
 void Voxelizer::prepareMipmap(GLuint aGridDimension, const FrameGraph & aGraph)
 {
-    mOccupancy = {GL_TEXTURE_3D};
-    // For creation
-    graphics::bind(mOccupancy);
-
-    if (mControl.mLinearFiltering)
-    {
-        glTextureParameteri(mOccupancy, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
-        glTextureParameteri(mOccupancy, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-    }
-
-    GLsizei levels = GLsizei(std::log2(aGridDimension)) + 1;
-    glTextureStorage3D(mOccupancy, levels, GL_RGBA8, aGridDimension, aGridDimension, aGridDimension);
-
-    std::uint8_t * buffer =
-        (std::uint8_t *)glMapNamedBufferRange(mVoxelStore,
-                                              offsetof(VoxelsSsbo_glsl, mVoxels),
-                                              mVoxelsByteSize,
-                                              GL_MAP_READ_BIT);
-    std::vector<math::sdr::Rgba> textureData;
-    textureData.reserve(mVoxelsByteSize);
-    // Need to reorder: the buffer is stored Z-first
-    //for (std::size_t idx = 0; idx != mVoxelsByteSize; ++idx)
-    //{
-    //    textureData.push_back({0, 0, 0, 
-    //                          (std::uint8_t)((buffer[idx] == 1) ? 255 : 0)});
-    //}
-
-    unsigned int zStride = 1;
-    unsigned int xStride = aGridDimension * zStride;
-    unsigned int yStride = aGridDimension * xStride;
-
-    // The buffer is stored Z-first, whereas the 3D textures are Z-last
-    // We could either sample Z-first in the shader, or fix it here
-    for (unsigned int z = 0; z != aGridDimension; ++z)
-    {
-        for (unsigned int y = 0; y != aGridDimension; ++y)
-        {
-            for (unsigned int x = 0; x != aGridDimension; ++x)
-            {
-                std::size_t idx = z * zStride + y * yStride + x * xStride;
-                textureData.push_back({0, 0, 0, 
-                                      (std::uint8_t)((buffer[idx] == 1) ? 255 : 0)});
-            }
-        }
-    }
-
-    glUnmapNamedBuffer(mVoxelStore);
-
-    glTextureSubImage3D(mOccupancy, 0,
-                        0, 0, 0, aGridDimension, aGridDimension, aGridDimension,
-                        GL_RGBA, GL_UNSIGNED_BYTE, textureData.data());
-
-    glGenerateTextureMipmap(mOccupancy);
-
     if (mControl.mComputeIrradianceMipmapping)
     {
         mipmapIrradiance(aGridDimension, aGraph);

src/apps/ch11_voxel/ch11_voxel/Voxelization.h

@@ -80,7 +80,6 @@ struct Voxelizer
     GLsizeiptr mVoxelsByteSize;
     math::Box<float> mSceneAabb; // Note: we could only keep min corner
     float mVoxelSize{0.f}; // World units
-    graphics::Texture mOccupancy{GL_TEXTURE_3D};
     graphics::Texture mAlbedo{GL_TEXTURE_3D};
     graphics::Texture mNormals{GL_TEXTURE_3D};
     graphics::Texture mIrradiance{GL_TEXTURE_3D};

src/apps/ch11_voxel/ch11_voxel/resources/shaders/ch11_InjectIrradiance.comp

@@ -159,6 +159,7 @@ void main()
     // Apply the voxel albedo to accumulated irradiance from all light sources
     irradiance *= albedo.rgb;
 
-    // TODO: store correct occupancy (1 might be correct)
+    // Note: At the level 0 (i.e. this level of the irradiance 3D texture)
+    // the occupancy (in alpha) is set to 1: the voxel is considered entirely occupied.
     imageStore(u_IrradianceImage, voxelCoord, vec4(irradiance, 1));
 }

src/apps/ch11_voxel/ch11_voxel/resources/shaders/ch11_VoxelConeTracing.glsl

@@ -13,7 +13,6 @@
 uniform float u_TanHalfAperture = M_PI / 6;
 uniform bool u_GridAlign;
 
-uniform sampler3D u_VoxelsAlbedoTexture;
 uniform sampler3D u_VoxelsIrradianceTexture;
 
 
@@ -110,7 +109,6 @@ vec4 traceCone(vec3 position_aabb, vec3 normal_aabb,
 
         vec3 position_uvw = samplePosition_aabb / (aVoxelSize * ub_GridDimension);
         // TODO: rename, this is not albedo but occupancy atm
-        vec4 albedo = textureLod(u_VoxelsAlbedoTexture, position_uvw, mipLevel);
         vec4 irradianceSample = textureLod(u_VoxelsIrradianceTexture, position_uvw, mipLevel);
 
         // irradiance marching, front to back compositing
@@ -127,7 +125,7 @@ vec4 traceCone(vec3 position_aabb, vec3 normal_aabb,
             marchedIrradiance.a += (1 - marchedIrradiance.a) * irradianceSample.a;
         #endif
 
-        occlusion += ((1.0f - occlusion) * albedo.a) / (1.0f + falloff * coneDiameter);
+        occlusion += ((1.0f - occlusion) * marchedIrradiance.a) / (1.0f + falloff * coneDiameter);
         // march the cone
         t += coneDiameter * samplingFactor;
     }