From 3a98f004f936055d64f3b92e70035419e6b4d61b Mon Sep 17 00:00:00 2001
From: Elias Naur <mail@eliasnaur.com>
Date: Tue, 14 Sep 2021 09:33:02 +0200
Subject: [PATCH] gpu/internal/opengl: reduce number of glsl shader variants

With the use of uniform buffers gone, we don't need the glsl 3.00 es
variant any longer.

We only support desktop OpenGL on macOS which is guaranteed to be
at least version 3.2, so we don't need the glsl 1.30 variant either.

Remove a test that depended on gl_VertexID which is not support in glsl
1.00 es.

Signed-off-by: Elias Naur <mail@eliasnaur.com>
---
 gpu/headless/driver_test.go   | 41 -----------------------------------
 gpu/internal/opengl/opengl.go | 12 ++--------
 2 files changed, 2 insertions(+), 51 deletions(-)

diff --git a/gpu/headless/driver_test.go b/gpu/headless/driver_test.go
index ddebc2b4..5e21fbd3 100644
--- a/gpu/headless/driver_test.go
+++ b/gpu/headless/driver_test.go
@@ -42,47 +42,6 @@ func TestFramebufferClear(t *testing.T) {
 	}
 }
 
-func TestSimpleShader(t *testing.T) {
-	b := newDriver(t)
-	sz := image.Point{X: 800, Y: 600}
-	vsh, fsh, err := newShaders(b, gio.Shader_simple_vert, gio.Shader_simple_frag)
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer vsh.Release()
-	defer fsh.Release()
-	fbo := newFBO(t, b, sz)
-	p, err := b.NewPipeline(driver.PipelineDesc{
-		VertexShader:   vsh,
-		FragmentShader: fsh,
-		PixelFormat:    driver.TextureFormatSRGBA,
-		Topology:       driver.TopologyTriangles,
-	})
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer p.Release()
-	d := driver.LoadDesc{
-		ClearColor: f32color.LinearFromSRGB(clearCol),
-		Action:     driver.LoadActionClear,
-	}
-	b.BeginRenderPass(fbo, d)
-	b.Viewport(0, 0, sz.X, sz.Y)
-	b.BindPipeline(p)
-	b.DrawArrays(0, 3)
-	b.EndRenderPass()
-	img := screenshot(t, b, fbo, sz)
-	if got := img.RGBAAt(0, 0); got != clearColExpect {
-		t.Errorf("got color %v, expected %v", got, clearColExpect)
-	}
-	// Just off the center to catch inverted triangles.
-	cx, cy := 300, 400
-	shaderCol := f32color.RGBA{R: .25, G: .55, B: .75, A: 1.0}
-	if got, exp := img.RGBAAt(cx, cy), shaderCol.SRGB(); got != f32color.NRGBAToRGBA(exp) {
-		t.Errorf("got color %v, expected %v", got, f32color.NRGBAToRGBA(exp))
-	}
-}
-
 func TestInputShader(t *testing.T) {
 	b := newDriver(t)
 	sz := image.Point{X: 800, Y: 600}
diff --git a/gpu/internal/opengl/opengl.go b/gpu/internal/opengl/opengl.go
index 51bc1e73..832512bf 100644
--- a/gpu/internal/opengl/opengl.go
+++ b/gpu/internal/opengl/opengl.go
@@ -888,18 +888,10 @@ func (b *Backend) NewFragmentShader(src shader.Sources) (driver.FragmentShader,
 }
 
 func (b *Backend) glslFor(src shader.Sources) string {
-	if b.glver[0] < 3 {
+	if b.gles {
 		return src.GLSL100ES
-	}
-	// OpenGL (ES) 3.0.
-	switch {
-	case b.gles:
-		return src.GLSL300ES
-	case b.glver[0] >= 4 || b.glver[1] >= 2:
-		// OpenGL 3.2 Core only accepts glsl 1.50 or newer.
+	} else {
 		return src.GLSL150
-	default:
-		return src.GLSL130
 	}
 }