fixed off-by-one error in the pixel height calculation

It should be max index / max size because 4096 / 4096 + 1 = 2, which means that two rows are allocated when a LUT1D with a size of 4096 fits in a 1D texture of 4096 pixels.

Signed-off-by: Hannes Vernooij <[email protected]>

Author: hannes-vernooij

src/OpenColorIO/ops/lut1d/Lut1DOpGPU.cpp

@@ -154,13 +154,13 @@ void GetLut1DGPUShaderProgram(GpuShaderCreatorRcPtr & shaderCreator,
 
     const unsigned long length      = lutData->getArray().getLength();
     const unsigned long width       = std::min(length, defaultMaxWidth);
-    const unsigned long height      = (length / defaultMaxWidth) + 1;
+    const unsigned long height      = ((length - 1) / defaultMaxWidth) + 1;
     const unsigned long numChannels = lutData->getArray().getNumColorComponents();
 
-    // Note: The 1D LUT needs a GPU texture for the Look-up table implementation. 
+    // Note: The 1D LUT needs a GPU texture for the Look-up table implementation.
     // However, the texture type & content may vary based on the number of channels
     // i.e. when all channels are identical a F32 Red GPU texture is enough.
- 
+
     const bool singleChannel = (numChannels == 1);
 
     // Adjust LUT texture to allow for correct 2d linear interpolation, if needed.
@@ -335,13 +335,13 @@ void GetLut1DGPUShaderProgram(GpuShaderCreatorRcPtr & shaderCreator,
     {
         const std::string str = name + "_computePos(" + shaderCreator->getPixelName();
 
-        ss.newLine() << shaderCreator->getPixelName() << ".r = " 
+        ss.newLine() << shaderCreator->getPixelName() << ".r = "
                      << ss.sampleTex2D(name, str + ".r)") << ".r;";
 
         ss.newLine() << shaderCreator->getPixelName() << ".g = "
                      << ss.sampleTex2D(name, str + ".g)") << (singleChannel ? ".r;" : ".g;");
 
-        ss.newLine() << shaderCreator->getPixelName() << ".b = " 
+        ss.newLine() << shaderCreator->getPixelName() << ".b = "
                      << ss.sampleTex2D(name, str + ".b)") << (singleChannel ? ".r;" : ".b;");
     }
     else