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/**
* Utilities for OpenGL shading language
*
* Brian Paul
* 9 April 2008
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <GL/glew.h>
#include <GL/glut.h>
#include "shaderutil.h"
GLboolean
ShadersSupported(void)
{
const char *version = (const char *) glGetString(GL_VERSION);
if (version[0] == '2' && version[1] == '.') {
return GL_TRUE;
}
else if (glutExtensionSupported("GL_ARB_vertex_shader")
&& glutExtensionSupported("GL_ARB_fragment_shader")
&& glutExtensionSupported("GL_ARB_shader_objects")) {
fprintf(stderr, "Warning: Trying ARB GLSL instead of OpenGL 2.x. This may not work.\n");
return GL_TRUE;
}
return GL_TRUE;
}
GLuint
CompileShaderText(GLenum shaderType, const char *text)
{
GLuint shader;
GLint stat;
shader = glCreateShader(shaderType);
glShaderSource(shader, 1, (const GLchar **) &text, NULL);
glCompileShader(shader);
glGetShaderiv(shader, GL_COMPILE_STATUS, &stat);
if (!stat) {
GLchar log[1000];
GLsizei len;
glGetShaderInfoLog(shader, 1000, &len, log);
fprintf(stderr, "Error: problem compiling shader: %s\n", log);
exit(1);
}
else {
/*printf("Shader compiled OK\n");*/
}
return shader;
}
/**
* Read a shader from a file.
*/
GLuint
CompileShaderFile(GLenum shaderType, const char *filename)
{
const int max = 100*1000;
int n;
char *buffer = (char*) malloc(max);
GLuint shader;
FILE *f;
f = fopen(filename, "r");
if (!f) {
fprintf(stderr, "Unable to open shader file %s\n", filename);
return 0;
}
n = fread(buffer, 1, max, f);
/*printf("read %d bytes from shader file %s\n", n, filename);*/
if (n > 0) {
buffer[n] = 0;
shader = CompileShaderText(shaderType, buffer);
}
else {
return 0;
}
fclose(f);
free(buffer);
return shader;
}
GLuint
LinkShaders(GLuint vertShader, GLuint fragShader)
{
GLuint program = glCreateProgram();
assert(vertShader || fragShader);
if (fragShader)
glAttachShader(program, fragShader);
if (vertShader)
glAttachShader(program, vertShader);
glLinkProgram(program);
/* check link */
{
GLint stat;
glGetProgramiv(program, GL_LINK_STATUS, &stat);
if (!stat) {
GLchar log[1000];
GLsizei len;
glGetProgramInfoLog(program, 1000, &len, log);
fprintf(stderr, "Shader link error:\n%s\n", log);
return 0;
}
}
return program;
}
void
SetUniformValues(GLuint program, struct uniform_info uniforms[])
{
GLuint i;
for (i = 0; uniforms[i].name; i++) {
uniforms[i].location
= glGetUniformLocation(program, uniforms[i].name);
switch (uniforms[i].type) {
case GL_INT:
case GL_SAMPLER_1D:
case GL_SAMPLER_2D:
case GL_SAMPLER_3D:
case GL_SAMPLER_CUBE:
case GL_SAMPLER_2D_RECT_ARB:
glUniform1i(uniforms[i].location,
(GLint) uniforms[i].value[0]);
break;
case GL_FLOAT:
glUniform1fv(uniforms[i].location, 1, uniforms[i].value);
break;
case GL_FLOAT_VEC2:
glUniform2fv(uniforms[i].location, 1, uniforms[i].value);
break;
case GL_FLOAT_VEC3:
glUniform3fv(uniforms[i].location, 1, uniforms[i].value);
break;
case GL_FLOAT_VEC4:
glUniform4fv(uniforms[i].location, 1, uniforms[i].value);
break;
default:
abort();
}
}
}
/** Get list of uniforms used in the program */
GLuint
GetUniforms(GLuint program, struct uniform_info uniforms[])
{
GLint n, max, i;
glGetProgramiv(program, GL_ACTIVE_UNIFORMS, &n);
glGetProgramiv(program, GL_ACTIVE_UNIFORM_MAX_LENGTH, &max);
for (i = 0; i < n; i++) {
GLint size, len;
GLenum type;
char name[100];
glGetActiveUniform(program, i, 100, &len, &size, &type, name);
uniforms[i].name = strdup(name);
uniforms[i].size = size;
uniforms[i].type = type;
uniforms[i].location = glGetUniformLocation(program, name);
}
uniforms[i].name = NULL; /* end of list */
return n;
}
void
PrintUniforms(const struct uniform_info uniforms[])
{
GLint i;
printf("Uniforms:\n");
for (i = 0; uniforms[i].name; i++) {
printf(" %d: %s size=%d type=0x%x loc=%d value=%g, %g, %g, %g\n",
i,
uniforms[i].name,
uniforms[i].size,
uniforms[i].type,
uniforms[i].location,
uniforms[i].value[0],
uniforms[i].value[1],
uniforms[i].value[2],
uniforms[i].value[3]);
}
}
/** Get list of attribs used in the program */
GLuint
GetAttribs(GLuint program, struct attrib_info attribs[])
{
GLint n, max, i;
glGetProgramiv(program, GL_ACTIVE_ATTRIBUTES, &n);
glGetProgramiv(program, GL_ACTIVE_ATTRIBUTE_MAX_LENGTH, &max);
for (i = 0; i < n; i++) {
GLint size, len;
GLenum type;
char name[100];
glGetActiveAttrib(program, i, 100, &len, &size, &type, name);
attribs[i].name = strdup(name);
attribs[i].size = size;
attribs[i].type = type;
attribs[i].location = glGetAttribLocation(program, name);
}
attribs[i].name = NULL; /* end of list */
return n;
}
void
PrintAttribs(const struct attrib_info attribs[])
{
GLint i;
printf("Attribs:\n");
for (i = 0; attribs[i].name; i++) {
printf(" %d: %s size=%d type=0x%x loc=%d\n",
i,
attribs[i].name,
attribs[i].size,
attribs[i].type,
attribs[i].location);
}
}
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