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>

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)