//-----------------------------------------------------------------------------
// Shader - Shader From a Buffer
//-----------------------------------------------------------------------------
bool shader::loadBuffer( const char* buffer, int length, int shaderType ) {
GLint shaderStatus(0);
GLuint shaderId( 0 );
if ( !programId ) {
programId = glCreateProgram();
if ( !programId ) {
std::cerr << "ERROR: Unable to create a shader program." << std::endl;
return false;
}
}
shaderId = glCreateShader( shaderType ); // Fragment shader or Vertex Shader
glShaderSource( shaderId, 1, (const GLchar**)&buffer, (const GLint*)&length );
glCompileShader( shaderId );
glGetShaderiv( shaderId, GL_COMPILE_STATUS, &shaderStatus );
if ( shaderStatus != GL_TRUE ) {
printShaderError( 0, shaderId );
return false;
}
glAttachShader( programId, shaderId );
shaderIds.push_back( shaderId );
printGlError("General shader loading error");
return true;
}
/**
* Creates a shader program. The two shader programs (vertex and
* fragment) were already compiled.
*
* @param vertShaderid A handle to the vertex shader
* @param fragShaderid A handle to the fragment shader
* @param shaderProgId A handle to the shader program.
* @return 0 if successful, -1 if error
*/
GLint Shader::createShaderProgram(GLint vertShaderid, GLint fragShaderid, GLuint *shaderProgId) {
int rc = 0;
// get a handle to the shader program
shaderProgramid = glCreateProgram();
// connect the shaders subprogram to the "main" program
glAttachShader(shaderProgramid, vertShaderid);
rc = glGetError();
if (rc != GL_NO_ERROR) {
fprintf(stderr,"error in attach shaders \n");
rc = -1;
goto err;
}
glAttachShader(shaderProgramid, fragShaderid);
rc = glGetError();
if (rc != GL_NO_ERROR) {
fprintf(stderr,"error in attach shaders \n");
rc = -1;
goto err;
}
// bind a varialbe before linking
//glBindAttribLocation(shaderProgramid, 7, "testNormal");
glLinkProgram(shaderProgramid);
// check for errors
glGetProgramiv(shaderProgramid, GL_LINK_STATUS, &rc);
if (rc != GL_TRUE) {
rc = -1;
GLsizei length;
GLsizei bufSize = 0;
char *error = NULL;
fprintf(stderr,"Error when creating a shader program \n");
//fputs("Error when creating a shader \n",stderr);
glGetProgramiv(shaderProgramid, GL_INFO_LOG_LENGTH, &bufSize);
error = (char *) malloc(bufSize*sizeof(char)+1);
if (error != NULL) {
glGetProgramInfoLog(shaderProgramid, bufSize, &length, error);
fprintf(stderr,"%s \n", error);
}
if (error != NULL) free(error);
} else rc = 0;
shaderStatus(); // may want to remove it.
if (shaderProgId != NULL) *shaderProgId = shaderProgramid;
err:
return (rc);
}
//-----------------------------------------------------------------------------
// Shader - Compilation
//-----------------------------------------------------------------------------
bool shader::compile() {
if (shaderIds.empty()) {
std::cerr << "WARNING: Attempted to compile a shader program without input" << std::endl;
return false;
}
GLint shaderStatus(0);
glLinkProgram(programId);
glGetProgramiv(programId, GL_LINK_STATUS, &shaderStatus);
if (shaderStatus != GL_TRUE) {
std::cerr << "\nWARNING: A GLSL Shader Error has occurred\n";
for ( int i = 0; i < shaderIds.size(); ++i )
printShaderError(programId, shaderIds[ i ]);
return false;
}
printGlError("Error compiling shader");
return true;
}
