329 lines
7.1 KiB
C
329 lines
7.1 KiB
C
/**
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* "Mandelbrot" shader demo. Uses the example shaders from
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* chapter 15 (or 18) of the OpenGL Shading Language "orange" book.
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* 15 Jan 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 char *FragProgFile = "CH18-mandel.frag.txt";
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static char *VertProgFile = "CH18-mandel.vert.txt";
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/* program/shader objects */
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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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struct uniform_info {
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const char *name;
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GLuint size;
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GLint location;
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GLfloat value[4];
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};
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static struct uniform_info Uniforms[] = {
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/* vert */
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{ "LightPosition", 3, -1, { 0.1, 0.1, 9.0, 0} },
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{ "SpecularContribution", 1, -1, { 0.5, 0, 0, 0 } },
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{ "DiffuseContribution", 1, -1, { 0.5, 0, 0, 0 } },
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{ "Shininess", 1, -1, { 20.0, 0, 0, 0 } },
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/* frag */
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{ "MaxIterations", 1, -1, { 12, 0, 0, 0 } },
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{ "Zoom", 1, -1, { 0.125, 0, 0, 0 } },
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{ "Xcenter", 1, -1, { -1.5, 0, 0, 0 } },
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{ "Ycenter", 1, -1, { .005, 0, 0, 0 } },
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{ "InnerColor", 3, -1, { 1, 0, 0, 0 } },
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{ "OuterColor1", 3, -1, { 0, 1, 0, 0 } },
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{ "OuterColor2", 3, -1, { 0, 0, 1, 0 } },
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{ NULL, 0, 0, { 0, 0, 0, 0 } }
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};
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static GLint win = 0;
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static GLfloat xRot = 0.0f, yRot = 0.0f, zRot = 0.0f;
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static GLint uZoom, uXcenter, uYcenter;
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static GLfloat zoom = 1.0, xCenter = -1.5, yCenter = 0.0;
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static void
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Redisplay(void)
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{
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glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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/* set interactive uniform parameters */
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glUniform1fv_func(uZoom, 1, &zoom);
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glUniform1fv_func(uXcenter, 1, &xCenter);
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glUniform1fv_func(uYcenter, 1, &yCenter);
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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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glRotatef(zRot, 0.0f, 0.0f, 1.0f);
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glBegin(GL_POLYGON);
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glTexCoord2f(0, 0); glVertex2f(-1, -1);
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glTexCoord2f(1, 0); glVertex2f( 1, -1);
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glTexCoord2f(1, 1); glVertex2f( 1, 1);
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glTexCoord2f(0, 1); glVertex2f(-1, 1);
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glEnd();
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glPopMatrix();
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glFinish();
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glFlush();
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glutSwapBuffers();
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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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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, -6.0f);
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}
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static void
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CleanUp(void)
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{
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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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}
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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 'z':
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zoom *= 0.9;
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break;
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case 'Z':
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zoom /= 0.9;
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break;
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case 27:
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CleanUp();
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exit(0);
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break;
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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 = 0.1 * zoom;
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(void) x;
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(void) y;
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switch(key) {
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case GLUT_KEY_UP:
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yCenter += step;
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break;
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case GLUT_KEY_DOWN:
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yCenter -= step;
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break;
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case GLUT_KEY_LEFT:
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xCenter -= step;
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break;
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case GLUT_KEY_RIGHT:
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xCenter += step;
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break;
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}
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glutPostRedisplay();
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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, "mandelbrot: problem compiling shader: %s\n", log);
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exit(1);
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}
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else {
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printf("Shader compiled OK\n");
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}
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}
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/**
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* Read a shader from a file.
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*/
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static void
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ReadShader(GLuint shader, const char *filename)
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{
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const int max = 100*1000;
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int n;
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char *buffer = (char*) malloc(max);
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FILE *f = fopen(filename, "r");
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if (!f) {
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fprintf(stderr, "mandelbrot: Unable to open shader file %s\n", filename);
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exit(1);
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}
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n = fread(buffer, 1, max, f);
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printf("mandelbrot: read %d bytes from shader file %s\n", n, filename);
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if (n > 0) {
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buffer[n] = 0;
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LoadAndCompileShader(shader, buffer);
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}
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fclose(f);
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free(buffer);
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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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else {
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fprintf(stderr, "Link success!\n");
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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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const char *version;
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GLint i;
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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("Warning: this program expects OpenGL 2.0\n");
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/*exit(1);*/
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}
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GetExtensionFuncs();
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vertShader = glCreateShader_func(GL_VERTEX_SHADER);
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ReadShader(vertShader, VertProgFile);
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fragShader = glCreateShader_func(GL_FRAGMENT_SHADER);
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ReadShader(fragShader, FragProgFile);
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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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for (i = 0; Uniforms[i].name; i++) {
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Uniforms[i].location
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= glGetUniformLocation_func(program, Uniforms[i].name);
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printf("Uniform %s location: %d\n", Uniforms[i].name,
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Uniforms[i].location);
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switch (Uniforms[i].size) {
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case 1:
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glUniform1fv_func(Uniforms[i].location, 1, Uniforms[i].value);
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break;
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case 2:
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glUniform2fv_func(Uniforms[i].location, 1, Uniforms[i].value);
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break;
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case 3:
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glUniform3fv_func(Uniforms[i].location, 1, Uniforms[i].value);
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break;
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case 4:
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glUniform4fv_func(Uniforms[i].location, 1, Uniforms[i].value);
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break;
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default:
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abort();
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}
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}
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uZoom = glGetUniformLocation_func(program, "Zoom");
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uXcenter = glGetUniformLocation_func(program, "Xcenter");
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uYcenter = glGetUniformLocation_func(program, "Ycenter");
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assert(glGetError() == 0);
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glClearColor(0.4f, 0.4f, 0.8f, 0.0f);
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printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
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assert(glIsProgram_func(program));
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assert(glIsShader_func(fragShader));
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assert(glIsShader_func(vertShader));
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glColor3f(1, 0, 0);
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}
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static void
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ParseOptions(int argc, char *argv[])
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{
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int i;
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for (i = 1; i < argc; i++) {
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if (strcmp(argv[i], "-fs") == 0) {
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FragProgFile = argv[i+1];
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}
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else if (strcmp(argv[i], "-vs") == 0) {
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VertProgFile = argv[i+1];
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}
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}
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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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glutInitWindowPosition( 0, 0);
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glutInitWindowSize(400, 400);
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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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ParseOptions(argc, argv);
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Init();
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glutMainLoop();
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return 0;
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}
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