fix missing texture reduction scale uniform

fix #129

Author: hypengw

src/Scene/Pkg/Parse/Uniform/UniformSource.cpp

@@ -964,6 +964,11 @@ auto ShadowUniformSource::Evaluate(ref<dyn<UniformUpdateContext>>,
 
 auto TextureUniformSource::Describe(mut_ref<dyn<UniformBindingSink>> sink) const
     -> Result<empty, UniformError> {
+    auto reduction = Bind(sink,
+                          TextureUniformOutput::ReductionScale,
+                          "g_TextureReductionScale"_str,
+                          UniformValueShape::Float(u32(1)));
+    if (reduction.is_err()) return reduction;
     for (usize index {}; index < WE_GLTEX_NAMES.len(); ++index) {
         auto resolution = Bind(sink,
                                TextureResolutionOutput(index.to_primitive()),
@@ -1002,7 +1007,9 @@ auto TextureUniformSource::Evaluate(ref<dyn<UniformUpdateContext>> context,
                                     mut_ref<dyn<UniformValueSink>> sink) const
     -> Result<empty, UniformError> {
     UniformWriter writer(sink);
-    auto          resources = context->Resources();
+    // Authored pixel offsets use unreduced texture coordinates; no global reduction is applied.
+    writer.Write(TextureUniformOutput::ReductionScale, 1.0f);
+    auto resources = context->Resources();
     for (usize index {}; index < WE_GLTEX_NAMES.len(); ++index) {
         auto texture = resources->Texture(index);
         if (texture.is_none()) continue;

src/Scene/Pkg/Parse/Uniform/UniformSource.cppm

@@ -83,11 +83,12 @@ enum class AudioUniformOutput : rstd::uint32_t
 
 enum class TextureUniformOutput : rstd::uint32_t
 {
-    Resolution0  = 0,
-    Mipmap0      = 16,
-    Rotation0    = 32,
-    Translation0 = 48,
-    Texel0       = 64,
+    Resolution0    = 0,
+    Mipmap0        = 16,
+    Rotation0      = 32,
+    Translation0   = 48,
+    Texel0         = 64,
+    ReductionScale = 80,
 };
 
 enum class ParticleTrailUniformOutput : rstd::uint32_t

tests/tests/scene-runtime/scene_runtime_tests.cpp

@@ -85,16 +85,21 @@ class ShapeSink {
         } else if (name == "g_LightsPosition"_str) {
             light_position_shape = shape;
             found_light_position = true;
+        } else if (name == "g_TextureReductionScale"_str) {
+            texture_reduction_shape = shape;
+            found_texture_reduction = true;
         }
         return rstd::Ok(true);
     }
 
     owe::UniformValueShape model_shape;
     owe::UniformValueShape spectrum_shape;
     owe::UniformValueShape light_position_shape;
+    owe::UniformValueShape texture_reduction_shape;
     bool                   found_model { false };
     bool                   found_spectrum { false };
     bool                   found_light_position { false };
+    bool                   found_texture_reduction { false };
 };
 
 class UpdateContext {
@@ -434,6 +439,23 @@ TEST(ShadowUniformSource, UsesAuthoredCascadeExtentAndLightObjectFrame) {
     EXPECT_FLOAT_EQ(atlas[usize(8)], 2.0f / 3.0f);
 }
 
+TEST(TextureUniformSource, PublishesUnreducedTextureScale) {
+    owe::TextureUniformSource source;
+    scene_test::ShapeSink     binding_sink;
+    auto                      bindings = rstd::dyn<owe::UniformBindingSink>::from_ref(binding_sink);
+    ASSERT_TRUE(source.Describe(bindings.as_mut_ref()).is_ok());
+    ASSERT_TRUE(binding_sink.found_texture_reduction);
+    EXPECT_EQ(binding_sink.texture_reduction_shape.scalar, owe::UniformScalarType::Float32);
+    EXPECT_EQ(binding_sink.texture_reduction_shape.kind, owe::UniformValueKind::Linear);
+    EXPECT_EQ(binding_sink.texture_reduction_shape.min_elements, u32(1));
+    EXPECT_EQ(binding_sink.texture_reduction_shape.max_elements, u32(1));
+
+    owe::SceneFrame frame;
+    auto scale = scene_test::Capture(frame, source, owe::TextureUniformOutput::ReductionScale);
+    ASSERT_EQ(scale.size(), usize(1));
+    EXPECT_FLOAT_EQ(scale[usize()], 1.0f);
+}
+
 TEST(TextureUniformSource, StaticTextureUsesIdentityTransform) {
     owe::SceneFrame                    frame;
     scene_test::StaticTextureResources resources;