Fix Vertex Attribute Specification Octahedral

For octahedral compressed normals/tangents, we use vec4 in the shader
regardless of whether a normal/tangent does/doesn't exist

For the case where we only have a normal vector, we need to specify that
there are only two components being used when calling glVertexAttrib

Before we would always specify that there were 4 components, and used
offsets to determine where in the vertex buffer to read data from but
this doesn't work on all platforms

drivers/gles2/rasterizer_storage_gles2.cpp

@@ -2309,7 +2309,7 @@ void RasterizerStorageGLES2::mesh_add_surface(RID p_mesh, uint32_t p_format, VS:
 					// UNLESS tangent exists and is also compressed
 					// then it will be oct16 encoded along with tangent
 					attribs[i].normalized = GL_TRUE;
-					attribs[i].size = 4;
+					attribs[i].size = 2;
 					attribs[i].type = GL_SHORT;
 					attributes_stride += 4;
 				} else {
@@ -2330,6 +2330,7 @@ void RasterizerStorageGLES2::mesh_add_surface(RID p_mesh, uint32_t p_format, VS:
 			case VS::ARRAY_TANGENT: {
 				if (p_format & VS::ARRAY_FLAG_USE_OCTAHEDRAL_COMPRESSION) {
 					attribs[i].enabled = false;
+					attribs[VS::ARRAY_NORMAL].size = 4;
 					if (p_format & VS::ARRAY_COMPRESS_TANGENT && p_format & VS::ARRAY_COMPRESS_NORMAL) {
 						// normal and tangent will each be oct16 (2 bytes each)
 						// pack into single vec4<GL_BYTE> for memory bandwidth

drivers/gles3/rasterizer_storage_gles3.cpp

@@ -3404,7 +3404,7 @@ void RasterizerStorageGLES3::mesh_add_surface(RID p_mesh, uint32_t p_format, VS:
 					// UNLESS tangent exists and is also compressed
 					// then it will be oct16 encoded along with tangent
 					attribs[i].normalized = GL_TRUE;
-					attribs[i].size = 4;
+					attribs[i].size = 2;
 					attribs[i].type = GL_SHORT;
 					attributes_stride += 4;
 				} else {
@@ -3425,6 +3425,7 @@ void RasterizerStorageGLES3::mesh_add_surface(RID p_mesh, uint32_t p_format, VS:
 			case VS::ARRAY_TANGENT: {
 				if (p_format & VS::ARRAY_FLAG_USE_OCTAHEDRAL_COMPRESSION) {
 					attribs[i].enabled = false;
+					attribs[VS::ARRAY_NORMAL].size = 4;
 					if (p_format & VS::ARRAY_COMPRESS_TANGENT && p_format & VS::ARRAY_COMPRESS_NORMAL) {
 						// normal and tangent will each be oct16 (2 bytes each)
 						// pack into single vec4<GL_BYTE> for memory bandwidth