require standardDerivatives glsl extension

src/mol-gl/shader-code.ts

@@ -17,7 +17,6 @@ const shaderCodeId = idFactory();
 
 type ShaderExtensionsValue = 'required' | 'optional'
 export interface ShaderExtensions {
-    readonly standardDerivatives?: ShaderExtensionsValue
     readonly fragDepth?: ShaderExtensionsValue
     readonly drawBuffers?: ShaderExtensionsValue
     readonly shaderTextureLod?: ShaderExtensionsValue
@@ -163,7 +162,7 @@ export const CylindersShaderCode = ShaderCode('cylinders', cylinders_vert, cylin
 
 import { text_vert } from './shader/text.vert';
 import { text_frag } from './shader/text.frag';
-export const TextShaderCode = ShaderCode('text', text_vert, text_frag, { standardDerivatives: 'required', drawBuffers: 'optional' });
+export const TextShaderCode = ShaderCode('text', text_vert, text_frag, { drawBuffers: 'optional' });
 
 import { lines_vert } from './shader/lines.vert';
 import { lines_frag } from './shader/lines.frag';
@@ -171,7 +170,7 @@ export const LinesShaderCode = ShaderCode('lines', lines_vert, lines_frag, { dra
 
 import { mesh_vert } from './shader/mesh.vert';
 import { mesh_frag } from './shader/mesh.frag';
-export const MeshShaderCode = ShaderCode('mesh', mesh_vert, mesh_frag, { standardDerivatives: 'optional', drawBuffers: 'optional' });
+export const MeshShaderCode = ShaderCode('mesh', mesh_vert, mesh_frag, { drawBuffers: 'optional' });
 
 import { directVolume_vert } from './shader/direct-volume.vert';
 import { directVolume_frag } from './shader/direct-volume.frag';
@@ -209,11 +208,9 @@ function getDefinesCode(defines: ShaderDefines) {
 }
 
 function getGlsl100FragPrefix(extensions: WebGLExtensions, shaderExtensions: ShaderExtensions) {
-    const prefix: string[] = [];
-    if (shaderExtensions.standardDerivatives) {
-        prefix.push('#extension GL_OES_standard_derivatives : enable');
-        prefix.push('#define enabledStandardDerivatives');
-    }
+    const prefix: string[] = [
+        '#extension GL_OES_standard_derivatives : enable'
+    ];
     if (shaderExtensions.fragDepth) {
         if (extensions.fragDepth) {
             prefix.push('#extension GL_EXT_frag_depth : enable');
@@ -268,9 +265,6 @@ function getGlsl300FragPrefix(gl: WebGL2RenderingContext, extensions: WebGLExten
         `layout(location = 0) out highp ${outTypes[0] || 'vec4'} out_FragData0;`
     ];
 
-    if (shaderExtensions.standardDerivatives) {
-        prefix.push('#define enabledStandardDerivatives');
-    }
     if (shaderExtensions.fragDepth) {
         prefix.push('#define enabledFragDepth');
     }

src/mol-gl/shader/mesh.frag.ts

@@ -19,14 +19,10 @@ void main() {
     #include clip_pixel
 
     // Workaround for buggy gl_FrontFacing (e.g. on some integrated Intel GPUs)
-    #if defined(enabledStandardDerivatives)
-        vec3 fdx = dFdx(vViewPosition);
-        vec3 fdy = dFdy(vViewPosition);
-        vec3 faceNormal = normalize(cross(fdx,fdy));
-        bool frontFacing = dot(vNormal, faceNormal) > 0.0;
-    #else
-        bool frontFacing = dot(vNormal, vViewPosition) < 0.0;
-    #endif
+    vec3 fdx = dFdx(vViewPosition);
+    vec3 fdy = dFdy(vViewPosition);
+    vec3 faceNormal = normalize(cross(fdx,fdy));
+    bool frontFacing = dot(vNormal, faceNormal) > 0.0;
 
     #if defined(dFlipSided)
         interior = frontFacing;
@@ -48,7 +44,7 @@ void main() {
         #ifdef dIgnoreLight
             gl_FragColor = material;
         #else
-            #if defined(dFlatShaded) && defined(enabledStandardDerivatives)
+            #if defined(dFlatShaded)
                 vec3 normal = -faceNormal;
             #else
                 vec3 normal = -normalize(vNormal);

src/mol-gl/webgl/extensions.ts

@@ -36,13 +36,11 @@ export function createExtensions(gl: GLRenderingContext): WebGLExtensions {
     if (elementIndexUint === null) {
         throw new Error('Could not find support for "element_index_uint"');
     }
-
     const standardDerivatives = getStandardDerivatives(gl);
-    if (isDebugMode && standardDerivatives === null) {
-        // - non-support handled downstream (flat shading option is ignored)
-        // - can't be a required extension because it is not supported by `headless-gl`
-        console.log('Could not find support for "standard_derivatives"');
+    if (standardDerivatives === null) {
+        throw new Error('Could not find support for "standard_derivatives"');
     }
+
     const textureFloat = getTextureFloat(gl);
     if (isDebugMode && textureFloat === null) {
         console.log('Could not find support for "texture_float"');