shader.c

#include <stdlib.h>
#include <stdio.h>

#include "util.h"
#include "shader.h"

static void show_info_log(GLuint object, PFNGLGETSHADERIVPROC glGet__iv, PFNGLGETSHADERINFOLOGPROC glGet__InfoLog) {
	GLint log_length;
	char *log;

	glGet__iv(object, GL_INFO_LOG_LENGTH, &log_length);
	log = malloc((size_t) log_length);
	glGet__InfoLog(object, log_length, NULL, log);
	fprintf(stderr, "%s", log);
	free(log);
}

GLuint make_shader(GLenum type, const char *filename) {
	GLint length;
	GLchar *source = file_contents(filename, &length);
	GLuint shader;
	GLint shader_ok;

	if(!source) {
		return 0;
	}

	shader = glCreateShader(type);
	glShaderSource(shader, 1, (const char **)&source, &length);
	free(source);
	glCompileShader(shader);

	glGetShaderiv(shader, GL_COMPILE_STATUS, &shader_ok);
	if(!shader_ok) {
		fprintf(stderr, "Failed to compile %s:\n", filename);
		show_info_log(shader, glGetShaderiv, glGetShaderInfoLog);
		glDeleteShader(shader);
		return 0;
	}

	return shader;
}

GLuint make_program(GLuint vertex_shader, GLuint fragment_shader)
{
	GLint program_ok;

	GLuint program = glCreateProgram();

	glAttachShader(program, vertex_shader);
	glAttachShader(program, fragment_shader);
	glLinkProgram(program);

	glGetProgramiv(program, GL_LINK_STATUS, &program_ok);
	if(!program_ok) {
		fprintf(stderr, "Failed to link shader program:\n");
		show_info_log(program, glGetProgramiv, glGetProgramInfoLog);
		glDeleteProgram(program);
		return 0;
	}
	return program;
}