Access the object uniforms relative to gl_InstanceIndex

filament/src/details/View.cpp

@@ -557,7 +557,7 @@ void FView::prepare(FEngine& engine, DriverApi& driver, ArenaScope& arena,
                 const size_t count = std::max(size_t(16u), (4u * merged.size() + 2u) / 3u);
                 mRenderableUBOSize = uint32_t(count * sizeof(PerRenderableData));
                 driver.destroyBufferObject(mRenderableUbh);
-                mRenderableUbh = driver.createBufferObject(mRenderableUBOSize,
+                mRenderableUbh = driver.createBufferObject(mRenderableUBOSize + sizeof(PerRenderableUib),
                         BufferObjectBinding::UNIFORM, BufferUsage::DYNAMIC);
             } else {
                 // TODO: should we shrink the underlying UBO at some point?

libs/filabridge/include/private/filament/UibStructs.h

@@ -211,7 +211,7 @@ static_assert(sizeof(PerRenderableData) == 256,
 
 struct alignas(256) PerRenderableUib { // NOLINT(cppcoreguidelines-pro-type-member-init)
     static constexpr utils::StaticString _name{ "ObjectUniforms" };
-    PerRenderableData data[1];
+    PerRenderableData data[64];
 };
 // PerRenderableUib must have an alignment of 256 to be compatible with all versions of GLES.
 static_assert(sizeof(PerRenderableUib) <= 16384,

libs/filamat/src/UibGenerator.cpp

@@ -149,7 +149,7 @@ UniformInterfaceBlock const& UibGenerator::getPerViewUib() noexcept  {
 UniformInterfaceBlock const& UibGenerator::getPerRenderableUib() noexcept {
     static UniformInterfaceBlock uib =  UniformInterfaceBlock::Builder()
             .name(PerRenderableUib::_name)
-            .add("data", 1, "PerRenderableData", sizeof(PerRenderableData))
+            .add("data", 64, "PerRenderableData", sizeof(PerRenderableData))
             .build();
     return uib;
 }

shaders/src/getters.fs

@@ -141,5 +141,11 @@ highp vec4 getCascadeLightSpacePosition(uint cascade) {
 #endif
 
 PerRenderableData getObjectUniforms() {
+#if defined(MATERIAL_HAS_INSTANCES)
+    // the material manages instancing, all instances share the same uniform block.
     return objectUniforms.data[0];
+#else
+     // automatic instancing was used, each instance has its own uniform block.
+    return objectUniforms.data[instance_index];
+#endif
 }

shaders/src/getters.vs

@@ -18,7 +18,13 @@ mat4 getLightFromWorldMatrix() {
 }
 
 PerRenderableData getObjectUniforms() {
+#if defined(MATERIAL_HAS_INSTANCES)
+    // the material manages instancing, all instances share the same uniform block.
     return objectUniforms.data[0];
+#else
+    // automatic instancing was used, each instance has its own uniform block.
+    return objectUniforms.data[instance_index];
+#endif
 }
 
 /** @public-api */