renderer/cm: higher-quality tonemapping (#12204)

1 files changed, 20 insertions, 8 deletions

diff --git a/src/render/OpenGL.cpp b/src/render/OpenGL.cpp
index 19c07923..2f1bccb2 100644
--- a/src/render/OpenGL.cpp
+++ b/src/render/OpenGL.cpp
@@ -971,6 +971,7 @@ static void getCMShaderUniforms(SShader& shader) {
     shader.uniformLocations[SHADER_DST_TF_RANGE]      = glGetUniformLocation(shader.program, "dstTFRange");
     shader.uniformLocations[SHADER_TARGET_PRIMARIES]  = glGetUniformLocation(shader.program, "targetPrimaries");
     shader.uniformLocations[SHADER_MAX_LUMINANCE]     = glGetUniformLocation(shader.program, "maxLuminance");
+    shader.uniformLocations[SHADER_SRC_REF_LUMINANCE] = glGetUniformLocation(shader.program, "srcRefLuminance");
     shader.uniformLocations[SHADER_DST_MAX_LUMINANCE] = glGetUniformLocation(shader.program, "dstMaxLuminance");
     shader.uniformLocations[SHADER_DST_REF_LUMINANCE] = glGetUniformLocation(shader.program, "dstRefLuminance");
     shader.uniformLocations[SHADER_SDR_SATURATION]    = glGetUniformLocation(shader.program, "sdrSaturation");
@@ -1560,6 +1561,14 @@ static bool isSDR2HDR(const NColorManagement::SImageDescription& imageDescriptio
          targetImageDescription.transferFunction == NColorManagement::CM_TRANSFER_FUNCTION_HLG);
 }
 
+static bool isHDR2SDR(const NColorManagement::SImageDescription& imageDescription, const NColorManagement::SImageDescription& targetImageDescription) {
+    // might be too strict
+    return (imageDescription.transferFunction == NColorManagement::CM_TRANSFER_FUNCTION_ST2084_PQ ||
+            imageDescription.transferFunction == NColorManagement::CM_TRANSFER_FUNCTION_HLG) &&
+        (targetImageDescription.transferFunction == NColorManagement::CM_TRANSFER_FUNCTION_SRGB ||
+         targetImageDescription.transferFunction == NColorManagement::CM_TRANSFER_FUNCTION_GAMMA22);
+}
+
 void CHyprOpenGLImpl::passCMUniforms(SShader& shader, const NColorManagement::SImageDescription& imageDescription,
                                      const NColorManagement::SImageDescription& targetImageDescription, bool modifySDR, float sdrMinLuminance, int sdrMaxLuminance) {
     static auto PSDREOTF = CConfigValue<Hyprlang::INT>("render:cm_sdr_eotf");
@@ -1585,16 +1594,22 @@ void CHyprOpenGLImpl::passCMUniforms(SShader& shader, const NColorManagement::SI
     shader.setUniformMatrix4x2fv(SHADER_TARGET_PRIMARIES, 1, false, glTargetPrimaries);
 
     const bool needsSDRmod = modifySDR && isSDR2HDR(imageDescription, targetImageDescription);
+    const bool needsHDRmod = !needsSDRmod && isHDR2SDR(imageDescription, targetImageDescription);
 
     shader.setUniformFloat2(SHADER_SRC_TF_RANGE, imageDescription.getTFMinLuminance(needsSDRmod ? sdrMinLuminance : -1),
                             imageDescription.getTFMaxLuminance(needsSDRmod ? sdrMaxLuminance : -1));
     shader.setUniformFloat2(SHADER_DST_TF_RANGE, targetImageDescription.getTFMinLuminance(needsSDRmod ? sdrMinLuminance : -1),
                             targetImageDescription.getTFMaxLuminance(needsSDRmod ? sdrMaxLuminance : -1));
 
-    const float maxLuminance = imageDescription.luminances.max > 0 ? imageDescription.luminances.max : imageDescription.luminances.reference;
-    shader.setUniformFloat(SHADER_MAX_LUMINANCE, maxLuminance * targetImageDescription.luminances.reference / imageDescription.luminances.reference);
+    shader.setUniformFloat(SHADER_SRC_REF_LUMINANCE, imageDescription.getTFRefLuminance(-1));
+    shader.setUniformFloat(SHADER_DST_REF_LUMINANCE, targetImageDescription.getTFRefLuminance(-1));
+
+    const float maxLuminance =
+        needsHDRmod ? imageDescription.getTFMaxLuminance(-1) : (imageDescription.luminances.max > 0 ? imageDescription.luminances.max : imageDescription.luminances.reference);
+    shader.setUniformFloat(SHADER_MAX_LUMINANCE,
+                           maxLuminance * targetImageDescription.luminances.reference /
+                               (needsHDRmod ? imageDescription.getTFRefLuminance(-1) : imageDescription.luminances.reference));
     shader.setUniformFloat(SHADER_DST_MAX_LUMINANCE, targetImageDescription.luminances.max > 0 ? targetImageDescription.luminances.max : 10000);
-    shader.setUniformFloat(SHADER_DST_REF_LUMINANCE, targetImageDescription.luminances.reference);
     shader.setUniformFloat(SHADER_SDR_SATURATION, needsSDRmod && m_renderData.pMonitor->m_sdrSaturation > 0 ? m_renderData.pMonitor->m_sdrSaturation : 1.0f);
     shader.setUniformFloat(SHADER_SDR_BRIGHTNESS, needsSDRmod && m_renderData.pMonitor->m_sdrBrightness > 0 ? m_renderData.pMonitor->m_sdrBrightness : 1.0f);
     const auto cacheKey = std::make_pair(imageDescription.getId(), targetImageDescription.getId());
@@ -1710,11 +1725,8 @@ void CHyprOpenGLImpl::renderTextureInternal(SP<CTexture> tex, const CBox& box, c
     if (shader == &m_shaders->m_shCM) {
         shader->setUniformInt(SHADER_TEX_TYPE, texType);
         if (data.cmBackToSRGB) {
-            // revert luma changes to avoid black screenshots.
-            // this will likely not be 1:1, and might cause screenshots to be too bright, but it's better than pitch black.
-            imageDescription.luminances = {};
-            static auto PSDREOTF        = CConfigValue<Hyprlang::INT>("render:cm_sdr_eotf");
-            auto        chosenSdrEotf   = *PSDREOTF > 0 ? NColorManagement::CM_TRANSFER_FUNCTION_GAMMA22 : NColorManagement::CM_TRANSFER_FUNCTION_SRGB;
+            static auto PSDREOTF      = CConfigValue<Hyprlang::INT>("render:cm_sdr_eotf");
+            auto        chosenSdrEotf = *PSDREOTF > 0 ? NColorManagement::CM_TRANSFER_FUNCTION_GAMMA22 : NColorManagement::CM_TRANSFER_FUNCTION_SRGB;
             passCMUniforms(*shader, imageDescription, NColorManagement::SImageDescription{.transferFunction = chosenSdrEotf}, true, -1, -1);
         } else
             passCMUniforms(*shader, imageDescription);