// create shader
GLuint Shader::create_shader(const std::string &text, unsigned int type)
{
GLuint shader = glCreateShader(type);
if (0 == shader) {
std::cerr << "Error: Shader creation failed" << std::endl;
}
// shader name strings and length
const GLchar *shader_sources[1];
GLint shader_sources_lengh[1];
shader_sources[0] = text.c_str();
shader_sources_lengh[0] = text.length();
// compile the shader
glShaderSource(shader, 1, shader_sources, shader_sources_lengh);
glCompileShader(shader);
// check for compile errors
check_shader_error(shader, GL_COMPILE_STATUS, false, "Error: Shader "
"compilation failed: ");
return shader;
}
Shader::Shader(const std::string &fname)
{
// create new shader program
m_program = glCreateProgram();
// start creating shaders, could refer by enum if class is matching
// two file extensions can be anything, just a convention
m_shaders[0] = create_shader(load_shader(fname + ".vs"), GL_VERTEX_SHADER);
m_shaders[1] = create_shader(load_shader(fname + ".fs"), GL_FRAGMENT_SHADER);
// add all the loaded shaders to program
for (unsigned int i = 0; i < NUM_SHADERS; i++) {
glAttachShader(m_program, m_shaders[i]);
}
// point to attribute locations
// this is the position field in our Vertex, and that's what we bind to
glBindAttribLocation(m_program, 0, "pos");
// also bind the position of the texture coordinate as a shader attribute
glBindAttribLocation(m_program, 1, "tex");
// link the shader to program and check for errors
glLinkProgram(m_program);
check_shader_error(m_program, GL_LINK_STATUS, true,
"Error: Program linking failed: ");
// make sure program is valid after linking
glValidateProgram(m_program);
check_shader_error(m_program, GL_LINK_STATUS, true,
"Error: Program is invalid: ");
// figure out what handle refers to our transformation uniform, since we
// called it transform, that's what we look for here
m_uniforms[TRANSFORM_U] = glGetUniformLocation(m_program, "transform");
}
GLuint load_shader(GLenum type, char *filename)
{
GLuint shader;
GLint compile_status;
char *src;
compile_status = GL_TRUE;
shader = glCreateShader(type);
if (glIsShader(shader) == 0)
exit(-1);
src = load_file(filename);
if (src == NULL)
exit(-1);
glShaderSource(shader, 1, (const char*const*)&src, NULL);
glCompileShader(shader);
free(src);
if (check_shader_error(shader, compile_status, filename) == 1)
{
glDeleteShader(shader);
exit(-1);
}
return (shader);
}
