77 lines
2.4 KiB
C++
77 lines
2.4 KiB
C++
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//-----------------------------------------------------------------------------
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// Offscreen rendering in OpenGL using framebuffer objects.
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//
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// Copyright 2015 <whitequark@whitequark.org>
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//-----------------------------------------------------------------------------
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#include "gloffscreen.h"
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#include <cstring>
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#include <cstdio>
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#include <cstdlib>
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#include <GL/glew.h>
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GLOffscreen::GLOffscreen() : _pixels(NULL), _pixels_inv(NULL) {
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if(glewInit() != GLEW_OK)
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abort();
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glGenFramebuffers(1, &_framebuffer);
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glGenRenderbuffers(1, &_color_renderbuffer);
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glGenRenderbuffers(1, &_depth_renderbuffer);
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}
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GLOffscreen::~GLOffscreen() {
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glDeleteRenderbuffers(1, &_depth_renderbuffer);
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glDeleteRenderbuffers(1, &_color_renderbuffer);
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glDeleteFramebuffers(1, &_framebuffer);
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}
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bool GLOffscreen::begin(int width, int height) {
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if(_width != width || _height != height) {
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delete[] _pixels;
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delete[] _pixels_inv;
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_pixels = new uint32_t[width * height * 4];
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_pixels_inv = new uint32_t[width * height * 4];
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_width = width;
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_height = height;
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}
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glBindFramebuffer(GL_FRAMEBUFFER, _framebuffer);
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glBindRenderbuffer(GL_RENDERBUFFER, _color_renderbuffer);
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glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, _width, _height);
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glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
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GL_RENDERBUFFER, _color_renderbuffer);
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glBindRenderbuffer(GL_RENDERBUFFER, _depth_renderbuffer);
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glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, _width, _height);
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glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
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GL_RENDERBUFFER, _depth_renderbuffer);
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if(glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE)
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return true;
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glBindFramebuffer(GL_FRAMEBUFFER, 0);
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return false;
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}
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uint8_t *GLOffscreen::end() {
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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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glReadPixels(0, 0, _width, _height,
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GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, _pixels_inv);
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#else
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glReadPixels(0, 0, _width, _height,
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GL_BGRA, GL_UNSIGNED_INT_8_8_8_8, _pixels_inv);
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#endif
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/* in OpenGL coordinates, bottom is zero Y */
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for(int i = 0; i < _height; i++)
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memcpy(&_pixels[_width * i], &_pixels_inv[_width * (_height - i - 1)], _width * 4);
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glBindFramebuffer(GL_FRAMEBUFFER, 0);
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return (uint8_t*) _pixels;
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}
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