gpu: don't validate uniform locations

Sufficiently smart GPU drivers can eliminate unused uniforms across
shader types.

Fixes gio#158

Signed-off-by: Elias Naur <mail@eliasnaur.com>

gpu/gl/backend.go

@@ -488,7 +488,7 @@ func (b *Backend) NewProgram(vertShader, fragShader backend.ShaderSources) (back
 }
 
 func lookupUniform(funcs Functions, p Program, loc backend.UniformLocation) uniformLocation {
-	u := GetUniformLocation(funcs, p, loc.Name)
+	u := funcs.GetUniformLocation(p, loc.Name)
 	return uniformLocation{uniform: u, offset: loc.Offset, typ: loc.Type, size: loc.Size}
 }
 

gpu/gl/util.go

@@ -37,14 +37,6 @@ func CreateProgram(ctx Functions, vsSrc, fsSrc string, attribs []string) (Progra
 	return prog, nil
 }
 
-func GetUniformLocation(ctx Functions, prog Program, name string) Uniform {
-	loc := ctx.GetUniformLocation(prog, name)
-	if !loc.valid() {
-		panic(fmt.Errorf("uniform %s not found", name))
-	}
-	return loc
-}
-
 func createShader(ctx Functions, typ Enum, src string) (Shader, error) {
 	sh := ctx.CreateShader(typ)
 	if !sh.valid() {