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BradDaBug

OpenGL glReadPixels() isn't working

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Sorry for the code dump, but I've been fighting with this all day and I can't seem to figure out what's wrong. I can see a white quad in the middle of the screen, but all the .bmps that are written are just black. If I don't call glClear() the bitmaps have what looks like the window under the SDL window, except the colors are inverted and I can see a black box where the quad should be. Any ideas?
#include <iostream>
#include <sstream>
#include <GL/glew.h>
#include <SDL/SDL.h>
#include "utils.h"

int main(int argc, char** argv)
{
	int width = 640;
	int height = 480;

	SDL_Init(SDL_INIT_VIDEO | SDL_INIT_NOPARACHUTE);

	SDL_GL_SetAttribute( SDL_GL_RED_SIZE, 8 );
    SDL_GL_SetAttribute( SDL_GL_GREEN_SIZE, 8 );
    SDL_GL_SetAttribute( SDL_GL_BLUE_SIZE, 8 );
    SDL_GL_SetAttribute( SDL_GL_DEPTH_SIZE, 16 );

	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 0);

	SDL_SetVideoMode(width, height, 32, SDL_OPENGL);

	

	glMatrixMode(GL_PROJECTION);
	glPushMatrix();
	glLoadIdentity();
		
	gluPerspective(45.0f, (float)width/height, 1.0f, 1000.0f);

	glMatrixMode(GL_MODELVIEW);
	glPushMatrix();
	glLoadIdentity();
	
	gluLookAt(0, 0, 0, 0, 0, 1.0f, 0, 1.0f, 1);
	glViewport(0, 0, width, height);

	char* pixels = new char[width * height * 3];

	glClearColor(0, 0, 0, 0.0f);

	for (int i = 0; i < 10; i++)
	{
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

		glBegin(GL_QUADS);
			glVertex3f(1.0f, 1.0f, 10);
			glVertex3f(-1.0f, 1.0f, 10);
			glVertex3f(-1.0f, -1.0f, 10);
			glVertex3f(1.0f, -1.0f, 10);
		glEnd();

		memset(pixels, 128, width * height * 3);
		
		glReadPixels(0, 0, width, height, GL_RGB, GL_UNSIGNED_BYTE, pixels);
	
		std::stringstream ss;
		ss << "blah_" << i << ".bmp";
		WriteBitmap(ss.str(), pixels, width, height, 3);

		GLenum err = glGetError();
		if (err != GL_NO_ERROR)
			std::cout << "zomg!" << std::endl;
	}

	return 0;
}

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char* pixels = new char[width * height * 3]; != GL_UNSIGNED_BYTE

u need GLubyte * pixels = new GLubyte

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Cripes. I figured it out. The problem was where I copy/pasted a version of WriteBitmap() that accepted an array of floats to create the char array version, and didn't remove the scaling-1.0-to-255 code.

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