nanovg_gl_utils.h

Go to the documentation of this file.

//
// Copyright (c) 2009-2013 Mikko Mononen memon@inside.org
//
// This software is provided 'as-is', without any express or implied
// warranty.  In no event will the authors be held liable for any damages
// arising from the use of this software.
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
// 1. The origin of this software must not be misrepresented; you must not
//    claim that you wrote the original software. If you use this software
//    in a product, an acknowledgment in the product documentation would be
//    appreciated but is not required.
// 2. Altered source versions must be plainly marked as such, and must not be
//    misrepresented as being the original software.
// 3. This notice may not be removed or altered from any source distribution.
//
#ifndef NANOVG_GL_UTILS_H
#define NANOVG_GL_UTILS_H
 
struct NVGLUframebuffer {
        NVGcontext* ctx;
        GLuint fbo;
        GLuint rbo;
        GLuint texture;
        int image;
};
typedef struct NVGLUframebuffer NVGLUframebuffer;
 
// Helper function to create GL frame buffer to render to.
void nvgluBindFramebuffer(NVGLUframebuffer* fb);
NVGLUframebuffer* nvgluCreateFramebuffer(NVGcontext* ctx, int w, int h, int imageFlags);
void nvgluDeleteFramebuffer(NVGLUframebuffer* fb);
 
#endif // NANOVG_GL_UTILS_H
 
#ifdef NANOVG_GL_IMPLEMENTATION
 
#if defined(NANOVG_GL3) || defined(NANOVG_GLES2) || defined(NANOVG_GLES3)
// FBO is core in OpenGL 3>.
#       define NANOVG_FBO_VALID 1
#elif defined(NANOVG_GL2)
// On OS X including glext defines FBO on GL2 too.
#       ifdef __APPLE__
#               include <OpenGL/glext.h>
#               define NANOVG_FBO_VALID 1
#       endif
#endif
 
static GLint defaultFBO = -1;
 
NVGLUframebuffer* nvgluCreateFramebuffer(NVGcontext* ctx, int w, int h, int imageFlags)
{
#ifdef NANOVG_FBO_VALID
        GLint defaultFBO;
        GLint defaultRBO;
        NVGLUframebuffer* fb = NULL;
 
        glGetIntegerv(GL_FRAMEBUFFER_BINDING, &defaultFBO);
        glGetIntegerv(GL_RENDERBUFFER_BINDING, &defaultRBO);
 
        fb = (NVGLUframebuffer*)malloc(sizeof(NVGLUframebuffer));
        if (fb == NULL) goto error;
        memset(fb, 0, sizeof(NVGLUframebuffer));
 
        fb->image = nvgCreateImageRGBA(ctx, w, h, imageFlags | NVG_IMAGE_FLIPY | NVG_IMAGE_PREMULTIPLIED, NULL);
 
#if defined NANOVG_GL2
        fb->texture = nvglImageHandleGL2(ctx, fb->image);
#elif defined NANOVG_GL3
        fb->texture = nvglImageHandleGL3(ctx, fb->image);
#elif defined NANOVG_GLES2
        fb->texture = nvglImageHandleGLES2(ctx, fb->image);
#elif defined NANOVG_GLES3
        fb->texture = nvglImageHandleGLES3(ctx, fb->image);
#endif
 
        fb->ctx = ctx;
 
        // frame buffer object
        glGenFramebuffers(1, &fb->fbo);
        glBindFramebuffer(GL_FRAMEBUFFER, fb->fbo);
 
        // render buffer object
        glGenRenderbuffers(1, &fb->rbo);
        glBindRenderbuffer(GL_RENDERBUFFER, fb->rbo);
        glRenderbufferStorage(GL_RENDERBUFFER, GL_STENCIL_INDEX8, w, h);
 
        // combine all
        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, fb->texture, 0);
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, fb->rbo);
 
        if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
#ifdef GL_DEPTH24_STENCIL8
                // If GL_STENCIL_INDEX8 is not supported, try GL_DEPTH24_STENCIL8 as a fallback.
                // Some graphics cards require a depth buffer along with a stencil.
                glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, w, h);
                glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, fb->texture, 0);
                glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, fb->rbo);
 
                if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
#endif // GL_DEPTH24_STENCIL8
                        goto error;
        }
 
        glBindFramebuffer(GL_FRAMEBUFFER, defaultFBO);
        glBindRenderbuffer(GL_RENDERBUFFER, defaultRBO);
        return fb;
error:
        glBindFramebuffer(GL_FRAMEBUFFER, defaultFBO);
        glBindRenderbuffer(GL_RENDERBUFFER, defaultRBO);
        nvgluDeleteFramebuffer(fb);
        return NULL;
#else
        NVG_NOTUSED(ctx);
        NVG_NOTUSED(w);
        NVG_NOTUSED(h);
        NVG_NOTUSED(imageFlags);
        return NULL;
#endif
}
 
void nvgluBindFramebuffer(NVGLUframebuffer* fb)
{
#ifdef NANOVG_FBO_VALID
        if (defaultFBO == -1) glGetIntegerv(GL_FRAMEBUFFER_BINDING, &defaultFBO);
        glBindFramebuffer(GL_FRAMEBUFFER, fb != NULL ? fb->fbo : defaultFBO);
#else
        NVG_NOTUSED(fb);
#endif
}
 
void nvgluDeleteFramebuffer(NVGLUframebuffer* fb)
{
#ifdef NANOVG_FBO_VALID
        if (fb == NULL) return;
        if (fb->fbo != 0)
                glDeleteFramebuffers(1, &fb->fbo);
        if (fb->rbo != 0)
                glDeleteRenderbuffers(1, &fb->rbo);
        if (fb->image >= 0)
                nvgDeleteImage(fb->ctx, fb->image);
        fb->ctx = NULL;
        fb->fbo = 0;
        fb->rbo = 0;
        fb->texture = 0;
        fb->image = -1;
        free(fb);
#else
        NVG_NOTUSED(fb);
#endif
}
 
#endif // NANOVG_GL_IMPLEMENTATION