added vbo/varr points method

diff --git a/glpixels.c b/glpixels.c
index b04ee88..cae9499 100644 (file)
--- a/glpixels.c
+++ b/glpixels.c
@@ -2,10 +2,11 @@
 #include <stdlib.h>
 #include <math.h>
 #include <assert.h>
+#define GL_GLEXT_PROTOTYPES    1
 #include <GL/glut.h>
 
 enum {
-       MODE_VERTEX,
+       MODE_POINTS,
        MODE_DRAWPIX,
        MODE_TEXQUAD,
        MODE_TEXTRI,
@@ -25,8 +26,14 @@ int max_xscroll, max_yscroll;
 #define IMG_W  1024
 #define IMG_H  1024
 unsigned int img[IMG_W * IMG_H];
+float *varr, *carr;
+unsigned int vbo_pos, vbo_col;
+int varr_sz, carr_sz;
+
+int mode = MODE_POINTS;
+
+int have_vbo = 1;      /* TODO */
 
-int mode = MODE_DRAWPIX;
 
 int main(int argc, char **argv)
 {
@@ -53,6 +60,7 @@ int init(void)
        int i, j, xor, r, g, b;
        unsigned int *ptr;
        unsigned int tex;
+       float *vptr;
 
        ptr = img;
        for(i=0; i<IMG_H; i++) {
@@ -76,25 +84,89 @@ int init(void)
        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);
 
+       varr_sz = win_width * win_height * sizeof *varr * 2;
+       if(!(varr = malloc(varr_sz))) {
+               fprintf(stderr, "failed to allocate vertex array\n");
+               return -1;
+       }
+       carr_sz = win_width * win_height * sizeof *carr * 3;
+       if(!(carr = malloc(carr_sz))) {
+               fprintf(stderr, "failed to allocate color array\n");
+               return -1;
+       }
+
+       vptr = varr;
+       for(i=0; i<win_height; i++) {
+               for(j=0; j<win_width; j++) {
+                       vptr[0] = j;
+                       vptr[1] = i;
+                       vptr += 2;
+               }
+       }
+
+       if(have_vbo) {
+               glGenBuffers(1, &vbo_pos);
+               glBindBuffer(GL_ARRAY_BUFFER, vbo_pos);
+               glBufferData(GL_ARRAY_BUFFER, varr_sz, varr, GL_STATIC_DRAW);
+
+               glGenBuffers(1, &vbo_col);
+               glBindBuffer(GL_ARRAY_BUFFER, vbo_col);
+               glBufferData(GL_ARRAY_BUFFER, carr_sz, 0, GL_STREAM_DRAW);
+       }
+
        return 0;
 }
 
 void display(void)
 {
+       int i, j;
        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;
+       unsigned int *start = img + yoffs * IMG_W + xoffs;
+       float *vptr = varr;
 
        switch(mode) {
-       case MODE_VERTEX:
+       case MODE_POINTS:
                /* draw with points */
+               vptr = carr;
+               for(i=0; i<win_height; i++) {
+                       for(j=0; j<win_width; j++) {
+                               int r = start[j] & 0xff;
+                               int g = (start[j] >> 8) & 0xff;
+                               int b = (start[j] >> 16) & 0xff;
+                               vptr[0] = r / 255.0f;
+                               vptr[1] = g / 255.0f;
+                               vptr[2] = b / 255.0f;
+                               vptr += 3;
+                       }
+                       start += IMG_W;
+               }
+
+               if(have_vbo) {
+                       glBindBuffer(GL_ARRAY_BUFFER, vbo_pos);
+                       glVertexPointer(2, GL_FLOAT, 0, 0);
+                       glBindBuffer(GL_ARRAY_BUFFER, vbo_col);
+                       glBufferSubData(GL_ARRAY_BUFFER, 0, carr_sz, carr);
+                       glColorPointer(3, GL_FLOAT, 0, 0);
+                       glBindBuffer(GL_ARRAY_BUFFER, 0);
+               } else {
+                       glVertexPointer(2, GL_FLOAT, 0, varr);
+                       glColorPointer(3, GL_FLOAT, 0, carr);
+               }
+
+               glEnableClientState(GL_VERTEX_ARRAY);
+               glEnableClientState(GL_COLOR_ARRAY);
+
+               glDrawArrays(GL_POINTS, 0, win_width * win_height);
+
+               glDisableClientState(GL_VERTEX_ARRAY);
+               glDisableClientState(GL_COLOR_ARRAY);
                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;
 
@@ -120,6 +192,10 @@ void reshape(int x, int y)
 {
        glViewport(0, 0, x, y);
 
+       glMatrixMode(GL_PROJECTION);
+       glLoadIdentity();
+       glOrtho(0, x, 0, y, -1, 1);
+
        win_width = x;
        win_height = y;
        max_xscroll = IMG_W - win_width;