MCShader: use transformed attribute names in VertexFormat for Shader

This ensures that shader attributes are bound correctly. Shader calls
glBindAttributeLocation using the names in the VertexFormat, not the
names in the shader json. By constructing a custom VertexFormat, we can
get around this.

GitHub: #62

versions/1.17.1-fabric/src/main/kotlin/gg/essential/universal/shader/MCShader.kt

@@ -108,9 +108,17 @@ internal class MCShader(
                 //#endif
             }
 
-            val shaderVertexFormat = vertexFormat?.mc
+            val shaderVertexFormat = if (vertexFormat != null) {
+                // Shader calls glBindAttribLocation using the names in the VertexFormat, not the shader json...
+                // Easiest way to work around this is to construct a custom VertexFormat with our prefixed names.
+                VertexFormat(ImmutableMap.copyOf(
+                    transformer.attributes.withIndex()
+                        .associate { it.value to vertexFormat.mc.elements[it.index] }))
+            } else {
                 // Legacy fallback: The actual element doesn't matter here, Shader only cares about the names
-                ?: VertexFormat(ImmutableMap.copyOf(transformer.attributes.associateWith { VertexFormats.POSITION_ELEMENT }))
+                VertexFormat(ImmutableMap.copyOf(transformer.attributes.associateWith { VertexFormats.POSITION_ELEMENT }))
+            }
+
 
             val name = DigestUtils.sha1Hex(json).lowercase()
             return MCShader(Shader(factory, name, shaderVertexFormat), blendState)