Remove all dependencies on go-gl/gl from internal/graphics

internal/graphics/internal/shader/drawtexture.go

@@ -15,7 +15,6 @@
 package shader
 
 import (
-	"github.com/go-gl/gl"
 	"github.com/hajimehoshi/ebiten/internal/opengl"
 )
 
@@ -42,7 +41,6 @@ type TextureQuads interface {
 var initialized = false
 
 // TODO: Use unsafe.SizeOf?
-const uint16Size = 2
 const float32Size = 4
 
 func DrawTexture(c *opengl.Context, texture opengl.Texture, projectionMatrix [4][4]float64, quads TextureQuads, geo Matrix, color Matrix) error {
@@ -62,8 +60,8 @@ func DrawTexture(c *opengl.Context, texture opengl.Texture, projectionMatrix [4]
 	// TODO: Check performance
 	program := useProgramColorMatrix(glMatrix(projectionMatrix), geo, color)
 
-	gl.ActiveTexture(gl.TEXTURE0)
-	gl.Texture(texture).Bind(gl.TEXTURE_2D)
+	// TODO: Do we have to call gl.ActiveTexture(gl.TEXTURE0)?
+	texture.Bind()
 
 	vertexAttrLocation := program.GetAttributeLocation("vertex")
 	texCoordAttrLocation := program.GetAttributeLocation("tex_coord")
@@ -89,9 +87,9 @@ func DrawTexture(c *opengl.Context, texture opengl.Texture, projectionMatrix [4]
 			x1, y1, u1, v1,
 		)
 	}
-	gl.BufferSubData(gl.ARRAY_BUFFER, 0, float32Size*len(vertices), vertices)
-	gl.DrawElements(gl.TRIANGLES, 6*quads.Len(), gl.UNSIGNED_SHORT, uintptr(0))
+	c.BufferSubData(c.ArrayBuffer, vertices)
+	c.DrawElements(6 * quads.Len())
 
-	gl.Flush()
+	c.Flush()
 	return nil
 }

internal/graphics/internal/shader/program.go

@@ -22,6 +22,7 @@ var programColorMatrix opengl.Program
 
 func initialize(c *opengl.Context) error {
 	const size = 10000
+	const uint16Size = 2
 
 	var err error
 	shaders[shaderVertex].native, err = c.NewShader(c.VertexShader, shaders[shaderVertex].source)
@@ -41,6 +42,9 @@ func initialize(c *opengl.Context) error {
 		shaders[shaderColorMatrix].native,
 	}
 	programColorMatrix, err = c.NewProgram(shaders)
+	if err != nil {
+		return err
+	}
 
 	const stride = 4 * 4
 	s := float32Size * stride * size
@@ -57,7 +61,7 @@ func initialize(c *opengl.Context) error {
 	}
 	c.NewBuffer(c.ElementArrayBuffer, uint16Size*len(indices), indices, c.StaticDraw)
 
-	return err
+	return nil
 }
 
 var lastProgram opengl.Program = 0

internal/opengl/context.go

@@ -39,6 +39,10 @@ func (t Texture) Pixels(width, height int) ([]uint8, error) {
 	return pixels, nil
 }
 
+func (t Texture) Bind() {
+	gl.Texture(t).Bind(gl.TEXTURE_2D)
+}
+
 func (t Texture) Delete() {
 	gl.Texture(t).Delete()
 }
@@ -220,3 +224,16 @@ func (c *Context) NewBuffer(bufferType BufferType, size int, ptr interface{}, bu
 	gl.GenBuffer().Bind(gl.GLenum(bufferType))
 	gl.BufferData(gl.GLenum(bufferType), size, ptr, gl.GLenum(bufferUsageType))
 }
+
+func (c *Context) BufferSubData(bufferType BufferType, data []float32) {
+	const float32Size = 4
+	gl.BufferSubData(gl.GLenum(bufferType), 0, float32Size*len(data), data)
+}
+
+func (c *Context) DrawElements(len int) {
+	gl.DrawElements(gl.TRIANGLES, len, gl.UNSIGNED_SHORT, uintptr(0))
+}
+
+func (c *Context) Flush() {
+	gl.Flush()
+}