Added shader points and shader bitmap demos
This commit is contained in:
Brian
368
progs/glsl/bitmap.c
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368
progs/glsl/bitmap.c
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/**
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* Implement glRasterPos + glBitmap with textures + shaders.
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* Brian Paul
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* 14 May 2007
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*/
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#include <assert.h>
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#include <string.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <GL/gl.h>
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#include <GL/glut.h>
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#include <GL/glext.h>
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#include "extfuncs.h"
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static GLuint FragShader;
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static GLuint VertShader;
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static GLuint Program;
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static GLint Win = 0;
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static GLint WinWidth = 500, WinHeight = 500;
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static GLboolean Anim = GL_TRUE;
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static GLboolean Bitmap = GL_FALSE;
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static GLfloat Xrot = 20.0f, Yrot = 70.0f;
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static GLint uTex, uScale;
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static GLuint Textures[2];
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#define TEX_WIDTH 16
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#define TEX_HEIGHT 8
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static void
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BitmapText(const char *s)
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{
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while (*s) {
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glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
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s++;
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}
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}
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static void
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Redisplay(void)
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{
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static const GLfloat px[3] = { 1.2, 0, 0};
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static const GLfloat nx[3] = {-1.2, 0, 0};
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glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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glPushMatrix();
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glRotatef(Xrot, 1.0f, 0.0f, 0.0f);
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glRotatef(Yrot, 0.0f, 1.0f, 0.0f);
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glEnable(GL_LIGHTING);
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glPushMatrix();
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glScalef(0.5, 0.5, 0.5);
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glutSolidDodecahedron();
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glPopMatrix();
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glDisable(GL_LIGHTING);
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glColor3f(0, 1, 0);
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glBegin(GL_LINES);
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glVertex3f(-1, 0, 0);
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glVertex3f( 1, 0, 0);
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glEnd();
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glColor3f(1, 1, 0);
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if (Bitmap) {
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glRasterPos3fv(px);
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BitmapText("+X");
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glRasterPos3fv(nx);
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BitmapText("-X");
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}
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else {
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glUseProgram_func(Program);
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/* vertex positions (deltas) depend on texture size and window size */
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if (uScale != -1) {
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glUniform2f_func(uScale,
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2.0 * TEX_WIDTH / WinWidth,
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2.0 * TEX_HEIGHT / WinHeight);
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}
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/* draw +X */
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glBindTexture(GL_TEXTURE_2D, Textures[0]);
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glBegin(GL_QUADS);
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glTexCoord2f(0, 0); glVertex3fv(px);
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glTexCoord2f(1, 0); glVertex3fv(px);
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glTexCoord2f(1, 1); glVertex3fv(px);
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glTexCoord2f(0, 1); glVertex3fv(px);
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glEnd();
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/* draw -X */
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glBindTexture(GL_TEXTURE_2D, Textures[1]);
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glBegin(GL_QUADS);
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glTexCoord2f(0, 0); glVertex3fv(nx);
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glTexCoord2f(1, 0); glVertex3fv(nx);
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glTexCoord2f(1, 1); glVertex3fv(nx);
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glTexCoord2f(0, 1); glVertex3fv(nx);
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glEnd();
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glUseProgram_func(0);
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}
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glPopMatrix();
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glutSwapBuffers();
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}
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static void
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Idle(void)
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{
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Yrot = glutGet(GLUT_ELAPSED_TIME) * 0.01;
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glutPostRedisplay();
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}
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static void
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Reshape(int width, int height)
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{
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WinWidth = width;
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WinHeight = height;
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glViewport(0, 0, width, height);
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
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glMatrixMode(GL_MODELVIEW);
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glLoadIdentity();
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glTranslatef(0.0f, 0.0f, -10.0f);
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}
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static void
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Key(unsigned char key, int x, int y)
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{
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(void) x;
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(void) y;
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switch(key) {
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case ' ':
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case 'a':
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Anim = !Anim;
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if (Anim)
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glutIdleFunc(Idle);
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else
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glutIdleFunc(NULL);
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break;
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case 'b':
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Bitmap = !Bitmap;
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if (Bitmap)
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printf("Using glBitmap\n");
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else
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printf("Using billboard texture\n");
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break;
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case 27:
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glDeleteShader_func(FragShader);
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glDeleteShader_func(VertShader);
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glDeleteProgram_func(Program);
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glutDestroyWindow(Win);
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exit(0);
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}
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glutPostRedisplay();
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}
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static void
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SpecialKey(int key, int x, int y)
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{
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const GLfloat step = 0.125f;
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switch(key) {
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case GLUT_KEY_UP:
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Xrot -= step;
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break;
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case GLUT_KEY_DOWN:
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Xrot += step;
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break;
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case GLUT_KEY_LEFT:
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Yrot -= step;
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break;
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case GLUT_KEY_RIGHT:
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Yrot += step;
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break;
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}
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/*printf("Xrot: %f Yrot: %f\n", Xrot, Yrot);*/
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glutPostRedisplay();
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}
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static void
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MakeTexImage(const char *p, GLuint texobj)
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{
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GLubyte image[TEX_HEIGHT][TEX_WIDTH];
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GLuint i, j, k;
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for (i = 0; i < TEX_HEIGHT; i++) {
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for (j = 0; j < TEX_WIDTH; j++) {
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k = i * TEX_WIDTH + j;
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if (p[k] == ' ') {
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image[i][j] = 0;
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}
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else {
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image[i][j] = 255;
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}
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}
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}
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glBindTexture(GL_TEXTURE_2D, texobj);
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glTexImage2D(GL_TEXTURE_2D, 0, GL_INTENSITY, TEX_WIDTH, TEX_HEIGHT, 0,
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GL_RED, GL_UNSIGNED_BYTE, image);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 1);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
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}
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static void
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MakeBitmapTextures(void)
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{
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const char *px =
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" X X "
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" X X X "
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" X X X "
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" XXXXX X "
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" X X X "
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" X X X "
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" X X "
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" X X ";
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const char *nx =
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" X X "
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" X X "
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" X X "
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" XXXXX X "
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" X X "
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" X X "
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" X X "
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" X X ";
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glGenTextures(2, Textures);
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MakeTexImage(px, Textures[0]);
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MakeTexImage(nx, Textures[1]);
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}
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static void
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LoadAndCompileShader(GLuint shader, const char *text)
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{
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GLint stat;
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glShaderSource_func(shader, 1, (const GLchar **) &text, NULL);
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glCompileShader_func(shader);
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glGetShaderiv_func(shader, GL_COMPILE_STATUS, &stat);
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if (!stat) {
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GLchar log[1000];
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GLsizei len;
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glGetShaderInfoLog_func(shader, 1000, &len, log);
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fprintf(stderr, "fslight: problem compiling shader:\n%s\n", log);
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exit(1);
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}
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}
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static void
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CheckLink(GLuint prog)
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{
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GLint stat;
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glGetProgramiv_func(prog, GL_LINK_STATUS, &stat);
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if (!stat) {
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GLchar log[1000];
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GLsizei len;
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glGetProgramInfoLog_func(prog, 1000, &len, log);
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fprintf(stderr, "Linker error:\n%s\n", log);
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}
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}
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static void
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Init(void)
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{
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/* Fragment shader: modulate raster color by texture, discard fragments
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* with alpha < 1.0
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*/
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static const char *fragShaderText =
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"uniform sampler2D tex2d; \n"
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"void main() {\n"
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" vec4 c = texture2D(tex2d, gl_TexCoord[0].xy); \n"
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" if (c.w < 1.0) \n"
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" discard; \n"
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" gl_FragColor = c * gl_Color; \n"
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"}\n";
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/* Vertex shader: compute new vertex position based on incoming vertex pos,
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* texcoords and special scale factor.
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*/
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static const char *vertShaderText =
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"uniform vec2 scale; \n"
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"void main() {\n"
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" vec4 p = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
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" gl_Position.xy = p.xy + gl_MultiTexCoord0.xy * scale * p.w; \n"
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" gl_Position.zw = p.zw; \n"
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" gl_TexCoord[0] = gl_MultiTexCoord0; \n"
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" gl_FrontColor = gl_Color; \n"
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"}\n";
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const char *version;
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version = (const char *) glGetString(GL_VERSION);
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if (version[0] != '2' || version[1] != '.') {
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printf("This program requires OpenGL 2.x, found %s\n", version);
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exit(1);
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}
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printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
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GetExtensionFuncs();
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FragShader = glCreateShader_func(GL_FRAGMENT_SHADER);
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LoadAndCompileShader(FragShader, fragShaderText);
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VertShader = glCreateShader_func(GL_VERTEX_SHADER);
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LoadAndCompileShader(VertShader, vertShaderText);
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Program = glCreateProgram_func();
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glAttachShader_func(Program, FragShader);
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glAttachShader_func(Program, VertShader);
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glLinkProgram_func(Program);
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CheckLink(Program);
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glUseProgram_func(Program);
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uScale = glGetUniformLocation_func(Program, "scale");
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uTex = glGetUniformLocation_func(Program, "tex2d");
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if (uTex != -1) {
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glUniform1i_func(uTex, 0); /* tex unit 0 */
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}
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glUseProgram_func(0);
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glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
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glEnable(GL_DEPTH_TEST);
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glEnable(GL_NORMALIZE);
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glEnable(GL_LIGHT0);
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MakeBitmapTextures();
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}
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int
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main(int argc, char *argv[])
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{
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glutInit(&argc, argv);
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glutInitWindowSize(WinWidth, WinHeight);
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glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
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Win = glutCreateWindow(argv[0]);
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glutReshapeFunc(Reshape);
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glutKeyboardFunc(Key);
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glutSpecialFunc(SpecialKey);
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glutDisplayFunc(Redisplay);
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if (Anim)
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glutIdleFunc(Idle);
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Init();
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glutMainLoop();
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return 0;
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}
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