gpu,gpu/internal,internal/gl: replace BlitFramebuffer with CopyTexture

OpenGL ES 2.0 doesn't support glBlitFramebuffer, but does support
glCopyTexSubImage2D. Fortunately, we don't need the extra features of
glBlitFramebuffer anyway.

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

gpu/compute.go

@@ -692,10 +692,10 @@ func (g *compute) compactLayers() error {
 				continue
 			}
 			src := l.place.atlas.fbo
-			dst := atlas.fbo
+			dst := atlas.image
 			sz := l.rect.Size()
 			sr := image.Rectangle{Min: l.place.pos, Max: l.place.pos.Add(sz)}
-			g.ctx.BlitFramebuffer(dst, src, sr, l.newPlace.pos)
+			g.ctx.CopyTexture(dst, l.newPlace.pos, src, sr)
 			l.place.atlas.layers--
 			layers[i].place = l.newPlace
 		}

gpu/internal/d3d11/d3d11_windows.go

@@ -165,7 +165,7 @@ func (b *Backend) BeginFrame(target driver.RenderTarget, clear bool, viewport im
 	return &Framebuffer{ctx: b.ctx, dev: b.dev, renderTarget: renderTarget, foreign: true}
 }
 
-func (b *Backend) BlitFramebuffer(dst, src driver.Framebuffer, srect image.Rectangle, dorigin image.Point) {
+func (b *Backend) CopyTexture(dst driver.Texture, dstOrigin image.Point, src driver.Framebuffer, srcRect image.Rectangle) {
 	panic("not implemented")
 }
 

gpu/internal/driver/driver.go

@@ -45,7 +45,7 @@ type Device interface {
 	BindFragmentUniforms(buf Buffer)
 	BindStorageBuffer(binding int, buf Buffer)
 
-	BlitFramebuffer(dst, src Framebuffer, srcRect image.Rectangle, dstOrigin image.Point)
+	CopyTexture(dst Texture, dstOrigin image.Point, src Framebuffer, srcRect image.Rectangle)
 	MemoryBarrier()
 	DispatchCompute(x, y, z int)
 

gpu/internal/metal/metal_darwin.go

@@ -524,9 +524,9 @@ func (b *Backend) startBlit() C.CFTypeRef {
 	return b.blitEnc
 }
 
-func (b *Backend) BlitFramebuffer(dst, src driver.Framebuffer, srect image.Rectangle, dorig image.Point) {
+func (b *Backend) CopyTexture(dst driver.Texture, dorig image.Point, src driver.Framebuffer, srect image.Rectangle) {
 	enc := b.startBlit()
-	dstTex := dst.(*Framebuffer).texture
+	dstTex := dst.(*Texture).texture
 	srcTex := src.(*Framebuffer).texture
 	ssz := srect.Size()
 	C.blitEncCopyFromTexture(

gpu/internal/opengl/opengl.go

@@ -1166,15 +1166,16 @@ func (b *Backend) BindIndexBuffer(buf driver.Buffer) {
 	b.glstate.bindBuffer(b.funcs, gl.ELEMENT_ARRAY_BUFFER, gbuf.obj)
 }
 
-func (b *Backend) BlitFramebuffer(dst, src driver.Framebuffer, srect image.Rectangle, dorig image.Point) {
+func (b *Backend) CopyTexture(dst driver.Texture, dstOrigin image.Point, src driver.Framebuffer, srcRect image.Rectangle) {
-	b.glstate.bindFramebuffer(b.funcs, gl.DRAW_FRAMEBUFFER, dst.(*framebuffer).obj)
+	const unit = 0
+	oldTex := b.glstate.texUnits.binds[unit]
+	defer func() {
+		b.glstate.bindTexture(b.funcs, unit, oldTex)
+	}()
+	b.glstate.bindTexture(b.funcs, unit, dst.(*texture).obj)
 	b.glstate.bindFramebuffer(b.funcs, gl.READ_FRAMEBUFFER, src.(*framebuffer).obj)
-	drect := image.Rectangle{Min: dorig, Max: dorig.Add(srect.Size())}
+	sz := srcRect.Size()
-	b.funcs.BlitFramebuffer(
+	b.funcs.CopyTexSubImage2D(gl.TEXTURE_2D, 0, dstOrigin.X, dstOrigin.Y, srcRect.Min.X, srcRect.Min.Y, sz.X, sz.Y)
-		srect.Min.X, srect.Min.Y, srect.Max.X, srect.Max.Y,
-		drect.Min.X, drect.Min.Y, drect.Max.X, drect.Max.Y,
-		gl.COLOR_BUFFER_BIT,
-		gl.NEAREST)
 }
 
 func (f *framebuffer) ReadPixels(src image.Rectangle, pixels []byte) error {

internal/gl/gl_js.go

@@ -104,9 +104,6 @@ func (f *Functions) BlendEquation(mode Enum) {
 func (f *Functions) BlendFuncSeparate(srcRGB, dstRGB, srcA, dstA Enum) {
 	f.Ctx.Call("blendFunc", int(srcRGB), int(dstRGB), int(srcA), int(dstA))
 }
-func (f *Functions) BlitFramebuffer(sx0, sy0, sx1, sy1, dx0, dy0, dx1, dy1 int, mask Enum, filter Enum) {
-	panic("not implemented")
-}
 func (f *Functions) BufferData(target Enum, size int, usage Enum) {
 	f.Ctx.Call("bufferData", int(target), size, int(usage))
 }
@@ -128,6 +125,9 @@ func (f *Functions) ClearDepthf(d float32) {
 func (f *Functions) CompileShader(s Shader) {
 	f.Ctx.Call("compileShader", js.Value(s))
 }
+func (f *Functions) CopyTexSubImage2D(target Enum, level, xoffset, yoffset, x, y, width, height int) {
+	f.Ctx.Call("copyTexSubImage2D", int(target), level, xoffset, yoffset, x, y, width, height)
+}
 func (f *Functions) CreateBuffer() Buffer {
 	return Buffer(f.Ctx.Call("createBuffer"))
 }

internal/gl/gl_unix.go

@@ -51,6 +51,7 @@ typedef struct {
 	void (*glClearColor)(GLfloat red, GLfloat green, GLfloat blue, GLfloat alpha);
 	void (*glClearDepthf)(GLfloat d);
 	void (*glCompileShader)(GLuint shader);
+	void (*glCopyTexSubImage2D)(GLenum target, GLint level, GLint xoffset, GLint yoffset, GLint x, GLint y, GLsizei width, GLsizei height);
 	GLuint (*glCreateProgram)(void);
 	GLuint (*glCreateShader)(GLenum type);
 	void (*glDeleteBuffers)(GLsizei n, const GLuint *buffers);
@@ -199,6 +200,10 @@ static void glCompileShader(glFunctions *f, GLuint shader) {
 	f->glCompileShader(shader);
 }
 
+static void glCopyTexSubImage2D(glFunctions *f, GLenum target, GLint level, GLint xoffset, GLint yoffset, GLint x, GLint y, GLsizei width, GLsizei height) {
+	f->glCopyTexSubImage2D(target, level, xoffset, yoffset, x, y, width, height);
+}
+
 static GLuint glCreateProgram(glFunctions *f) {
 	return f->glCreateProgram();
 }
@@ -606,6 +611,7 @@ func (f *Functions) load(forceES bool) error {
 	f.f.glClearColor = must("glClearColor")
 	f.f.glClearDepthf = must("glClearDepthf")
 	f.f.glCompileShader = must("glCompileShader")
+	f.f.glCopyTexSubImage2D = must("glCopyTexSubImage2D")
 	f.f.glCreateProgram = must("glCreateProgram")
 	f.f.glCreateShader = must("glCreateShader")
 	f.f.glDeleteBuffers = must("glDeleteBuffers")
@@ -808,6 +814,10 @@ func (f *Functions) CompileShader(s Shader) {
 	C.glCompileShader(&f.f, C.GLuint(s.V))
 }
 
+func (f *Functions) CopyTexSubImage2D(target Enum, level, xoffset, yoffset, x, y, width, height int) {
+	C.glCopyTexSubImage2D(&f.f, C.GLenum(target), C.GLint(level), C.GLint(xoffset), C.GLint(yoffset), C.GLint(x), C.GLint(y), C.GLsizei(width), C.GLsizei(height))
+}
+
 func (f *Functions) CreateBuffer() Buffer {
 	C.glGenBuffers(&f.f, 1, &f.uints[0])
 	return Buffer{uint(f.uints[0])}

internal/gl/gl_windows.go

@@ -34,6 +34,7 @@ var (
 	_glDeleteQueries                       = LibGLESv2.NewProc("glDeleteQueries")
 	_glDeleteVertexArrays                  = LibGLESv2.NewProc("glDeleteVertexArrays")
 	_glCompileShader                       = LibGLESv2.NewProc("glCompileShader")
+	_glCopyTexSubImage2D                   = LibGLESv2.NewProc("glCopyTexSubImage2D")
 	_glGenBuffers                          = LibGLESv2.NewProc("glGenBuffers")
 	_glGenFramebuffers                     = LibGLESv2.NewProc("glGenFramebuffers")
 	_glGenVertexArrays                     = LibGLESv2.NewProc("glGenVertexArrays")
@@ -158,9 +159,6 @@ func (c *Functions) BlendEquation(mode Enum) {
 func (c *Functions) BlendFuncSeparate(srcRGB, dstRGB, srcA, dstA Enum) {
 	syscall.Syscall6(_glBlendFuncSeparate.Addr(), 4, uintptr(srcRGB), uintptr(dstRGB), uintptr(srcA), uintptr(dstA), 0, 0)
 }
-func (f *Functions) BlitFramebuffer(sx0, sy0, sx1, sy1, dx0, dy0, dx1, dy1 int, mask Enum, filter Enum) {
-	panic("not implemented")
-}
 func (c *Functions) BufferData(target Enum, size int, usage Enum) {
 	syscall.Syscall6(_glBufferData.Addr(), 4, uintptr(target), uintptr(size), 0, uintptr(usage), 0, 0)
 }
@@ -187,6 +185,9 @@ func (c *Functions) ClearDepthf(d float32) {
 func (c *Functions) CompileShader(s Shader) {
 	syscall.Syscall(_glCompileShader.Addr(), 1, uintptr(s.V), 0, 0)
 }
+func (f *Functions) CopyTexSubImage2D(target Enum, level, xoffset, yoffset, x, y, width, height int) {
+	syscall.Syscall9(_glCopyTexSubImage2D.Addr(), 8, uintptr(target), uintptr(level), uintptr(xoffset), uintptr(yoffset), uintptr(x), uintptr(y), uintptr(width), uintptr(height), 0)
+}
 func (c *Functions) CreateBuffer() Buffer {
 	var buf uintptr
 	syscall.Syscall(_glGenBuffers.Addr(), 2, 1, uintptr(unsafe.Pointer(&buf)), 0)