initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644 (file)
index 0000000..198a5c8
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+*.o
+*.swp
+glpixels

diff --git a/Makefile b/Makefile
new file mode 100644 (file)
index 0000000..bb38ce2
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,12 @@
+obj = glpixels.o
+bin = glpixels
+
+CFLAGS = -pedantic -Wall -g
+LDFLAGS = -lGL -lglut -lm
+
+$(bin): $(obj)
+       $(CC) -o $@ $(obj) $(LDFLAGS)
+
+.PHONY: clean
+clean:
+       rm -f $(obj) $(bin)

diff --git a/glpixels.c b/glpixels.c
new file mode 100644 (file)
index 0000000..b04ee88
--- /dev/null
+++ b/glpixels.c
@@ -0,0 +1,144 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <assert.h>
+#include <GL/glut.h>
+
+enum {
+       MODE_VERTEX,
+       MODE_DRAWPIX,
+       MODE_TEXQUAD,
+       MODE_TEXTRI,
+
+       NUM_MODES
+};
+
+int init(void);
+void display(void);
+void idle(void);
+void reshape(int x, int y);
+void keyb(unsigned char key, int x, int y);
+
+int win_width, win_height;
+int max_xscroll, max_yscroll;
+
+#define IMG_W  1024
+#define IMG_H  1024
+unsigned int img[IMG_W * IMG_H];
+
+int mode = MODE_DRAWPIX;
+
+int main(int argc, char **argv)
+{
+       glutInit(&argc, argv);
+       glutInitWindowSize(800, 600);
+       glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
+       glutCreateWindow("GL pixel drawing methods");
+
+       glutDisplayFunc(display);
+       glutReshapeFunc(reshape);
+       glutKeyboardFunc(keyb);
+       glutIdleFunc(idle);
+
+       if(init() == -1) {
+               return 1;
+       }
+       glutMainLoop();
+       return 0;
+}
+
+
+int init(void)
+{
+       int i, j, xor, r, g, b;
+       unsigned int *ptr;
+       unsigned int tex;
+
+       ptr = img;
+       for(i=0; i<IMG_H; i++) {
+               for(j=0; j<IMG_W; j++) {
+                       xor = i ^ j;
+                       r = (xor >> 1) & 0xff;
+                       g = xor & 0xff;
+                       b = (xor << 1) & 0xff;
+                       *ptr++ = r | (g << 8) | (b << 16);
+               }
+       }
+
+       glPixelStorei(GL_UNPACK_ROW_LENGTH, IMG_W);
+
+       win_width = glutGet(GLUT_WINDOW_WIDTH);
+       win_height = glutGet(GLUT_WINDOW_HEIGHT);
+
+       glGenTextures(1, &tex);
+       glBindTexture(GL_TEXTURE_2D, tex);
+       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+       glTexImage2D(GL_TEXTURE_2D, 1, GL_RGBA, win_width, win_height, 1, GL_RGBA, GL_UNSIGNED_BYTE, 0);
+
+       return 0;
+}
+
+void display(void)
+{
+       unsigned int tm = glutGet(GLUT_ELAPSED_TIME);
+       float t = tm / 256.0f;
+       int xoffs = (int)((sin(t) * 0.5f + 0.5f) * max_xscroll);
+       int yoffs = (int)((cos(t) * 0.5f + 0.5f) * max_yscroll);
+       unsigned int *start;
+
+       switch(mode) {
+       case MODE_VERTEX:
+               /* draw with points */
+               break;
+
+       case MODE_DRAWPIX:
+               /* draw with glDrawPixels */
+               start = img + yoffs * IMG_W + xoffs;
+               glDrawPixels(win_width, win_height, GL_RGBA, GL_UNSIGNED_BYTE, start);
+               break;
+
+       case MODE_TEXQUAD:
+               /* draw with textured quad */
+               break;
+
+       case MODE_TEXTRI:
+               /* draw with textured triangle */
+               break;
+       }
+
+       glutSwapBuffers();
+       assert(glGetError() == GL_NO_ERROR);
+}
+
+void idle(void)
+{
+       glutPostRedisplay();
+}
+
+void reshape(int x, int y)
+{
+       glViewport(0, 0, x, y);
+
+       win_width = x;
+       win_height = y;
+       max_xscroll = IMG_W - win_width;
+       max_yscroll = IMG_H - win_height;
+       if(max_xscroll < 0) max_xscroll = 0;
+       if(max_yscroll < 0) max_yscroll = 0;
+}
+
+void keyb(unsigned char key, int x, int y)
+{
+       switch(key) {
+       case 27:
+               exit(0);
+
+       case ' ':
+               mode = (mode + 1) % NUM_MODES;
+               break;
+
+       default:
+               break;
+       }
+}