Attachment 9393 Details for Bug 10483 – simple case for reading pixels

simple case for reading pixels

read_alpha.c (text/plain), 2.42 KB, created by Wei Wang on 2007-03-31 06:50:53 UTC

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Creator: Wei Wang

Created: 2007-03-31 06:50:53 UTC

Size: 2.42 KB

patch

obsolete

>#include "GL/glut.h"
>#include <string.h>
>#include <stdio.h>
>#include <unistd.h>
>#include <stdlib.h>
>#include <math.h>
>
>
>#define WIN_WIDTH 100
>#define WIN_HEIGHT 100
>#define TEX_WIDTH 8
>#define TEX_HEIGHT 4
>
>#define EPSILON_R 0.4
>#define EPSILON_G 0.4
>#define EPSILON_B 0.4
>#define EPSILON_A 0.4
>
>GLfloat read_buf[4 * TEX_WIDTH * TEX_HEIGHT];
>GLfloat tex_image2d[TEX_WIDTH][TEX_HEIGHT][3];
>GLint tex_name = 1;
>
>
>void init()
>{
>	glMatrixMode(GL_MODELVIEW);
>	glLoadIdentity();
>	glTranslatef(-1.0, -1.0, 0.0);
>	glScalef(2.0/WIN_WIDTH, 2.0/WIN_HEIGHT, 1.0);
>
>	glClearColor(0.0, 0.0, 0.0, 0.3);
>	glClear(GL_COLOR_BUFFER_BIT);
>
>	glDisable (GL_DITHER);
>}
>
>
>int check_pixels(GLint llx, GLint lly, GLint w, GLint h, 
>			GLfloat exp_r, GLfloat exp_g,
>			GLfloat exp_b, GLfloat exp_a)
>{
>	GLfloat *buf = NULL, color_r, color_g, color_b, color_a;
>	int x, y, pixel;
>
>	buf = (GLfloat *)malloc(w * h * sizeof(GLfloat) * 4);
>	if (buf == NULL)
>		return -2;
>	
>	glReadPixels(llx, lly, w, h, GL_RGBA, GL_FLOAT, buf);
>	
>        for (y = 0; y < h; y ++) {
>        for (x = 0; x < w; x ++) {
>                pixel = x + y * w;
>		color_r = buf[pixel*4];
>		color_g =  buf[pixel*4+1];
>		color_b =  buf[pixel*4+2];
>		color_a =  buf[pixel*4+3];
>
>		if (fabsf(color_r - exp_r) > EPSILON_R ||
>		    fabsf(color_g - exp_g) > EPSILON_G ||
>		    fabsf(color_b - exp_b) > EPSILON_B ||
>		    fabsf(color_a - exp_a) > EPSILON_A)  {
>
>                	printf("pixel[%d, %d]: %f %f %f %f\n", x, y,
>                        	buf[pixel*4], buf[pixel*4+1],
>	                        buf[pixel*4+2], buf[pixel*4+3]);
>		}
>        }
>        }
>
>	printf("\ncheck pixels done.\n");
>	if (buf)
>		free(buf);
>
>	return 0;
>}
>
>
>
>void display()
>{
>	GLint i, read_w = 0, read_h = 0, x = 0, y = 0, pixel;
>	
>	glClear(GL_COLOR_BUFFER_BIT);
>	if (glIsEnabled(GL_ALPHA_TEST) == GL_FALSE)
>		printf("Alpha test is disabled \n");
>
>	glColor4f(0.0, 0.1, 1.0, 0.8);
>	glBegin(GL_QUAD_STRIP);
>		glVertex2i(10, 10);
>		glVertex2i(10, 60);
>		glVertex2i(60, 10);
>		glVertex2i(60, 60);
>	glEnd();
>
>	check_pixels(10, 10, 50, 50, 0.0, 0.1, 1.0, 0.8);
>
>	glutSwapBuffers();
>
>}
>
>
>int main(int argc, char** argv)
>{
>	glutInit(&argc, argv);
>	glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGBA);
>	glutInitWindowSize (WIN_WIDTH, WIN_HEIGHT);
>	glutInitWindowPosition (100, 100);
>	glutCreateWindow ("hello");
>	init();
>	glutDisplayFunc(display);
>	glutMainLoop();
>}

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