From a0571c84673f01b05e6edeb901cca8ff5ae9a023 Mon Sep 17 00:00:00 2001 From: Tavian Barnes Date: Thu, 2 Jul 2009 18:12:16 +0000 Subject: Implement dmnsn_gl_read_canvas. --- libdimension/gl.c | 40 ++++++++++++++++++++++++++++++++++++++-- 1 file changed, 38 insertions(+), 2 deletions(-) (limited to 'libdimension/gl.c') diff --git a/libdimension/gl.c b/libdimension/gl.c index 3542a2d..e67551b 100644 --- a/libdimension/gl.c +++ b/libdimension/gl.c @@ -85,7 +85,43 @@ dmnsn_gl_write_canvas(const dmnsn_canvas *canvas) /* Read a canvas from a GL framebuffer. Returns NULL on failure. */ dmnsn_canvas * -dmnsn_gl_read_canvas() +dmnsn_gl_read_canvas(unsigned int x0, unsigned int y0, + unsigned int width, unsigned int height) { - return NULL; + dmnsn_canvas *canvas; + GLuint *pixels; /* Array of 32-bit ints in RGBA order */ + GLuint *pixel; + dmnsn_sRGB sRGB; + dmnsn_color *color; + unsigned int x, y; + + canvas = dmnsn_new_canvas(width, height); + if (!canvas) { + return NULL; + } + + pixels = malloc(4*width*height*sizeof(GLuint)); + if (!pixels) { + dmnsn_delete_canvas(canvas); + return NULL; + } + + glReadPixels(x0, y0, width, height, GL_RGBA, GL_UNSIGNED_INT, pixels); + + for (y = 0; y < height; ++y) { + for (x = 0; x < width; ++x) { + color = dmnsn_pixel_at(canvas, x, y); + pixel = pixels + 4*(y*width + x); + + sRGB.R = ((double)pixel[0])/UINT32_MAX; + sRGB.G = ((double)pixel[1])/UINT32_MAX; + sRGB.B = ((double)pixel[2])/UINT32_MAX; + + *color = dmnsn_color_from_sRGB(sRGB); + color->filter = ((double)pixel[3])/UINT32_MAX; + } + } + + free(pixels); + return canvas; } -- cgit v1.2.3