Implement FBO blit texture copy

This trick uses FBOs to allow for copying textures without the need for
special texture copy functions.

libobs-opengl/gl-helpers.c

@@ -56,10 +56,55 @@ bool gl_init_face(GLenum target, GLenum type, uint32_t num_levels,
 	return success;
 }
 
+static bool gl_copy_fbo(struct gs_device *device,
+		GLuint dst, GLenum dst_target,
+		GLuint src, GLenum src_target,
+		uint32_t width, uint32_t height,
+		enum gs_color_format format)
+{
+	struct fbo_info *fbo = get_fbo(device, width, height, format);
+	GLint last_fbo;
+	bool success = false;
+
+	if (!fbo)
+		return false;
+
+	if (!gl_get_integer_v(GL_READ_FRAMEBUFFER_BINDING, &last_fbo))
+		return false;
+	if (!gl_bind_framebuffer(GL_READ_FRAMEBUFFER, fbo->fbo))
+		return false;
+	if (!gl_bind_texture(dst_target, dst))
+		goto fail;
+
+	glFramebufferTexture2D(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + 0,
+			src_target, src, 0);
+	if (!gl_success("glFrameBufferTexture2D"))
+		goto fail;
+
+	glReadBuffer(GL_COLOR_ATTACHMENT0 + 0);
+	if (!gl_success("glReadBuffer"))
+		goto fail;
+
+	glCopyTexSubImage2D(dst_target, 0, 0, 0, 0, 0, width, height);
+	if (!gl_success("glCopyTexSubImage2D"))
+		goto fail;
+
+	success = true;
+
+fail:
+	if (!gl_bind_texture(dst_target, 0))
+		success = false;
+	if (!gl_bind_framebuffer(GL_READ_FRAMEBUFFER, last_fbo))
+		success = false;
+
+	return success;
+}
+
 bool gl_copy_texture(struct gs_device *device,
                      GLuint dst, GLenum dst_target,
                      GLuint src, GLenum src_target,
-                     uint32_t width, uint32_t height)
+                     uint32_t width, uint32_t height,
+                     enum gs_color_format format)
 {
 	bool success = false;
 
@@ -76,7 +121,11 @@ bool gl_copy_texture(struct gs_device *device,
 		success = gl_success("glCopyImageSubDataNV");
 
 	} else if (device->copy_type == COPY_TYPE_FBO_BLIT) {
-		/* TODO (implement FBOs) */
+		if (gl_copy_fbo(device, dst, dst_target, src,  src_target,
+					width, height, format))
+			success = true;
+		else
+			blog(LOG_ERROR, "gl_copy_texture failed");
 	}
 
 	return success;

libobs-opengl/gl-helpers.h

@@ -137,6 +137,12 @@ static inline bool gl_cull_face(GLenum faces)
 	return gl_success("glCullFace");
 }
 
+static inline bool gl_get_integer_v(GLenum pname, GLint *params)
+{
+	glGetIntegerv(pname, params);
+	return gl_success("glGetIntegerv");
+}
+
 extern bool gl_init_face(GLenum target, GLenum type, uint32_t num_levels,
 		GLenum format, GLint internal_format, bool compressed,
 		uint32_t width, uint32_t height, uint32_t size,
@@ -145,7 +151,8 @@ extern bool gl_init_face(GLenum target, GLenum type, uint32_t num_levels,
 extern bool gl_copy_texture(struct gs_device *device,
                             GLuint dst, GLenum dst_target,
                             GLuint src, GLenum src_target,
-                            uint32_t width, uint32_t height);
+                            uint32_t width, uint32_t height,
+			    enum gs_color_format format);
 
 extern bool gl_create_buffer(GLenum target, GLuint *buffer, GLsizeiptr size,
 		const GLvoid *data, GLenum usage);

libobs-opengl/gl-stagesurf.c

@@ -141,7 +141,7 @@ void device_stage_texture(device_t device, stagesurf_t dst, texture_t src)
 
 	if (!gl_copy_texture(device, dst->texture, GL_TEXTURE_2D,
 				tex2d->base.texture, GL_TEXTURE_2D,
-				dst->width, dst->height))
+				dst->width, dst->height, dst->format))
 		goto failed;
 
 	if (!gl_bind_texture(GL_TEXTURE_2D, dst->texture))

libobs-opengl/gl-subsystem.c

@@ -120,7 +120,7 @@ static bool gl_init_extensions(struct gs_device* device)
 	else if (ogl_ext_NV_copy_image)
 		device->copy_type = COPY_TYPE_NV;
 	else
-		device->copy_type = COPY_TYPE_FBO_BLIT; /* ?? */
+		device->copy_type = COPY_TYPE_FBO_BLIT;
 
 	return true;
 }
@@ -577,21 +577,18 @@ static bool get_tex_dimensions(texture_t tex, uint32_t *width, uint32_t *height)
  * This automatically manages FBOs so that render targets are always given
  * an FBO that matches their width/height/format to maximize optimization
  */
-static struct fbo_info *get_fbo(struct gs_device *device, texture_t tex)
+struct fbo_info *get_fbo(struct gs_device *device,
+		uint32_t width, uint32_t height, enum gs_color_format format)
 {
 	size_t i;
-	uint32_t width, height;
 	GLuint fbo;
 	struct fbo_info *ptr;
 
-	if (!get_tex_dimensions(tex, &width, &height))
-		return NULL;
-
 	for (i = 0; i < device->fbos.num; i++) {
 		ptr = device->fbos.array[i];
 
 		if (ptr->width  == width && ptr->height == height &&
-		    ptr->format == tex->format)
+		    ptr->format == format)
 			return ptr;
 	}
 
@@ -603,7 +600,7 @@ static struct fbo_info *get_fbo(struct gs_device *device, texture_t tex)
 	ptr->fbo                 = fbo;
 	ptr->width               = width;
 	ptr->height              = height;
-	ptr->format              = tex->format;
+	ptr->format              = format;
 	ptr->cur_render_target   = NULL;
 	ptr->cur_render_side     = 0;
 	ptr->cur_zstencil_buffer = NULL;
@@ -612,6 +609,16 @@ static struct fbo_info *get_fbo(struct gs_device *device, texture_t tex)
 	return ptr;
 }
 
+static inline struct fbo_info *get_fbo_by_tex(struct gs_device *device,
+		texture_t tex)
+{
+	uint32_t width, height;
+	if (!get_tex_dimensions(tex, &width, &height))
+		return NULL;
+
+	return get_fbo(device, width, height, tex->format);
+}
+
 static bool set_current_fbo(device_t device, struct fbo_info *fbo)
 {
 	if (device->cur_fbo != fbo) {
@@ -688,7 +695,7 @@ static bool set_target(device_t device, texture_t tex, int side, zstencil_t zs)
 	if (!tex)
 		return set_current_fbo(device, NULL);
 
-	fbo = get_fbo(device, tex);
+	fbo = get_fbo_by_tex(device, tex);
 	if (!fbo)
 		return false;
 
@@ -783,7 +790,7 @@ void device_copy_texture(device_t device, texture_t dst, texture_t src)
 
 	if (!gl_copy_texture(device, dst->texture, dst->gl_target,
 				src->texture, src->gl_target,
-				src2d->width, src2d->height))
+				src2d->width, src2d->height, src->format))
 		goto fail;
 
 	return;

libobs-opengl/gl-subsystem.h

@@ -479,6 +479,9 @@ struct gs_device {
 	struct fbo_info          *cur_fbo;
 };
 
+extern struct fbo_info *get_fbo(struct gs_device *device,
+		uint32_t width, uint32_t height, enum gs_color_format format);
+
 extern void                  gl_update(device_t device);
 
 extern struct gl_platform   *gl_platform_create(device_t device,