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/*
Create an OpenGL context without creating an OpenGL Window. for Windows.
*/
#include "OffscreenContext.h"
#include "printutils.h"
#include "imageutils.h"
#include "fbo.h"
#include <vector>
#include <GL/gl.h>
using namespace std;
struct OffscreenContext
{
// GLXContext openGLContext;
int width;
int height;
fbo_t *fbo;
};
void offscreen_context_init(OffscreenContext &ctx, int width, int height)
{
ctx.width = width;
ctx.height = height;
ctx.fbo = NULL;
}
void glewCheck() {
#ifdef DEBUG
cerr << "GLEW version " << glewGetString(GLEW_VERSION) << "\n";
cerr << (const char *)glGetString(GL_RENDERER) << "(" << (const char *)glGetString(GL_VENDOR) << ")\n"
<< "OpenGL version " << (const char *)glGetString(GL_VERSION) << "\n";
cerr << "Extensions: " << (const char *)glGetString(GL_EXTENSIONS) << "\n";
if (GLEW_ARB_framebuffer_object) {
cerr << "ARB_FBO supported\n";
}
if (GLEW_EXT_framebuffer_object) {
cerr << "EXT_FBO supported\n";
}
if (GLEW_EXT_packed_depth_stencil) {
cerr << "EXT_packed_depth_stencil\n";
}
#endif
}
OffscreenContext *create_offscreen_context(int w, int h)
{
OffscreenContext *ctx = new OffscreenContext;
offscreen_context_init( *ctx, w, h );
// before an FBO can be setup, a GLX context must be created
// this call alters ctx->xDisplay and ctx->openGLContext
// and ctx->xwindow if successfull
cerr << "WGL not implemented\n";
/*
if (!create_glx_dummy_context( *ctx )) {
return NULL;
}
glewInit(); //must come after Context creation and before FBO calls.
glewCheck();
ctx->fbo = fbo_new();
if (!fbo_init(ctx->fbo, w, h)) {
return NULL;
}
*/
ctx = NULL;
return ctx;
}
bool teardown_offscreen_context(OffscreenContext *ctx)
{
if (ctx) {
fbo_unbind(ctx->fbo);
fbo_delete(ctx->fbo);
return true;
}
return false;
}
/*!
Capture framebuffer from OpenGL and write it to the given filename as PNG.
*/
bool save_framebuffer(OffscreenContext *ctx, const char *filename)
{
if (!ctx || !filename) return false;
int samplesPerPixel = 4; // R, G, B and A
vector<GLubyte> pixels(ctx->width * ctx->height * samplesPerPixel);
glReadPixels(0, 0, ctx->width, ctx->height, GL_RGBA, GL_UNSIGNED_BYTE, &pixels[0]);
// Flip it vertically - images read from OpenGL buffers are upside-down
int rowBytes = samplesPerPixel * ctx->width;
unsigned char *flippedBuffer = (unsigned char *)malloc(rowBytes * ctx->height);
if (!flippedBuffer) {
std::cerr << "Unable to allocate flipped buffer for corrected image.";
return 1;
}
flip_image(&pixels[0], flippedBuffer, samplesPerPixel, ctx->width, ctx->height);
bool writeok = write_png(filename, flippedBuffer, ctx->width, ctx->height);
free(flippedBuffer);
return writeok;
}
void bind_offscreen_context(OffscreenContext *ctx)
{
if (ctx) fbo_bind(ctx->fbo);
}
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