graphics: Remove framebuffer's width/height

internal/graphics/command.go

@@ -122,11 +122,13 @@ func (c *drawImageCommand) Exec(context *opengl.Context) error {
 	if n == 0 {
 		return nil
 	}
+	_, h := c.dst.Size()
+	proj := glMatrix(c.dst.framebuffer.projectionMatrix(h))
 	p := programContext{
 		state:            &theOpenGLState,
 		program:          theOpenGLState.programTexture,
 		context:          context,
-		projectionMatrix: glMatrix(c.dst.framebuffer.projectionMatrix()),
+		projectionMatrix: proj,
 		texture:          c.src.texture.native,
 		geoM:             c.geo,
 		colorM:           c.color,
@@ -275,8 +277,6 @@ func (c *newScreenFramebufferImageCommand) Exec(context *opengl.Context) error {
 	}
 	f := &framebuffer{
 		native: context.ScreenFramebuffer(),
-		width:  c.width,
-		height: c.height,
 		flipY:  true,
 	}
 	c.result.framebuffer = f

internal/graphics/framebuffer.go

@@ -34,8 +34,6 @@ func orthoProjectionMatrix(left, right, bottom, top int) *[4][4]float64 {
 
 type framebuffer struct {
 	native    opengl.Framebuffer
-	width     int
-	height    int
 	flipY     bool
 	proMatrix *[4][4]float64
 }
@@ -47,8 +45,6 @@ func newFramebufferFromTexture(context *opengl.Context, texture *texture) (*fram
 	}
 	return &framebuffer{
 		native: native,
-		width:  texture.width,
-		height: texture.height,
 	}, nil
 }
 
@@ -60,16 +56,14 @@ func (f *framebuffer) setAsViewport(context *opengl.Context) error {
 	return context.SetViewport(f.native, width, height)
 }
 
-func (f *framebuffer) projectionMatrix() *[4][4]float64 {
+func (f *framebuffer) projectionMatrix(height int) *[4][4]float64 {
 	if f.proMatrix != nil {
 		return f.proMatrix
 	}
-	width := viewportSize
-	height := viewportSize
-	m := orthoProjectionMatrix(0, width, 0, height)
+	m := orthoProjectionMatrix(0, viewportSize, 0, viewportSize)
 	if f.flipY {
 		m[1][1] *= -1
-		m[1][3] += float64(f.height) / float64(height) * 2
+		m[1][3] += float64(height) / float64(viewportSize) * 2
 	}
 	f.proMatrix = m
 	return f.proMatrix

internal/graphics/image.go

@@ -112,7 +112,7 @@ func (i *Image) Pixels(context *opengl.Context) ([]uint8, error) {
 		return nil, err
 	}
 	f := i.framebuffer
-	return context.FramebufferPixels(f.native, f.width, f.height)
+	return context.FramebufferPixels(f.native, i.width, i.height)
 }
 
 func (i *Image) ReplacePixels(p []uint8) error {