Updates to lighting a bit

platform/darwin/src/gltf/GLTFMath.cpp

@@ -202,3 +202,14 @@ simd_float4x4 GLTFNormalMatrixFromModelMatrix(simd_float4x4 m) {
     } };
     return mout;
 }
+
+simd_double4x4 GLTFNormalMatrixFromModelMatrixD(simd_double4x4 m) {
+    simd_double3x3 nm = simd_inverse(simd_transpose(GLTFMatrixUpperLeft3x3D(m)));
+    simd_double4x4 mout = { {
+        { nm.columns[0][0], nm.columns[0][1], nm.columns[0][2], 0 },
+        { nm.columns[1][0], nm.columns[1][1], nm.columns[1][2], 0 },
+        { nm.columns[2][0], nm.columns[2][1], nm.columns[2][2], 0 },
+        {                0,                0,                0, 1 }
+    } };
+    return mout;
+}

platform/darwin/src/gltf/GLTFMath.hpp

@@ -130,6 +130,8 @@ simd_float3x3 GLTFTextureMatrixFromTransform(GLTFTextureTransform transform);
 
 simd_float4x4 GLTFNormalMatrixFromModelMatrix(simd_float4x4 m);
 
+simd_double4x4 GLTFNormalMatrixFromModelMatrixD(simd_double4x4 m);
+
 
 #ifdef __cplusplus
 }

platform/darwin/src/gltf/MetalRenderer+GLTFAsset.mm

@@ -372,6 +372,8 @@ simd_float3 double3_to_float3(simd_double3 input) {
             auto mvp = matrix_multiply(_projectionMatrix, model->_modelViewMatrix);
             auto mvpF = matrix_double_to_float(mvp);
             vertexUniforms.modelViewProjectionMatrix = mvpF;
+            auto normalMatrix = GLTFNormalMatrixFromModelMatrixD( model->_modelViewMatrix);
+            vertexUniforms.normalMatrix = matrix_double_to_float(normalMatrix);