GLSL Shader Test

gistfile1.txt

#include <string>
#include <vector>
#include <iterator>
#include <fstream>
#include <iostream>

#include <GL/gl.h>
#include <GL/glext.h>
#include <SDL/SDL.h>

//GLuint program_handle;

void create_and_attach_program();
void read_source_file(char* file, GLchar*** strings, GLint** lengths);

using namespace std;

int main(int argc, char** argv)
{
	SDL_Init(SDL_INIT_VIDEO);
	SDL_SetVideoMode(640, 480, 0, SDL_OPENGL);

	create_and_attach_program();

	glBegin(GL_TRIANGLES);
	glVertex2f(-1.00, 0.0);
	glVertex2f(1.0, 0.0);
	glVertex2f(0.0, 1.0);
	glEnd();

	SDL_GL_SwapBuffers();

	SDL_Delay(1000);
}

void read_source_file(char* file, GLsizei* count, GLchar*** strings, GLint** lengths)
{
	// read line lengths from file
	ifstream ifs(file);
	istream_iterator<char> iit(ifs), eof;
	vector<int> tmp_lengths;
	int length = 0;
	char currentChar;
	while(iit != eof) {
		currentChar = *iit++;
		if(currentChar == '\n') {
			tmp_lengths.push_back(++length);
			length = 0;
		} else {
			length++;
		}
	}
	// accept last line without final \n
	if(length > 0) tmp_lengths.push_back(length);
	// store line lengths in line array
	int lines = tmp_lengths.size();
	*count = lines;
	*lengths = new GLint[lines];
	for(int i=0; i<lines; ++i) (*lengths)[i] = tmp_lengths[i];

	// allocate space for string array
	*strings = new char*[lines];

	// read actual lines
	ifstream ifs2(file);
	istream_iterator<char> iit2(ifs2);
	for(int i=0; i<lines; ++i) {
		int length = tmp_lengths[i];
		char* str = new char[length+1];
		for(int l=0; l<length; ++l)
			str[l] = *iit2++;
		str[length] = '\0';
		(*strings)[i] = str;
	}
}

void create_and_attach_program()
{
	GLuint fs;
	GLuint program = glCreateProgram();
	// compile vertex shader
	fs = glCreateShader(GL_FRAGMENT_SHADER);
	glAttachShader(program, fs);
	GLchar** strings;
	GLint* lengths;
	GLsizei count;
	read_source_file("red.fs", &count, &strings, &lengths);	
	glShaderSource(fs, count, (const GLchar**) strings, lengths);
	glCompileShader(fs);
	GLint compileStatus;
	glGetObjectParameteriv(fs, GL_OBJECT_COMPILE_STATUS_ARB, &compileStatus);
	if(!compileStatus) {
		cout << "compilation error" << endl;
	}
	glLinkProgram(program);
	glUseProgram(program);
}