Helper methods from class

Angel.h

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+//////////////////////////////////////////////////////////////////////////////
+//
+//  --- Angel.h ---
+//
+//   The main header file for all examples from Angel 6th Edition
+//
+//////////////////////////////////////////////////////////////////////////////
+
+#ifndef __ANGEL_H__
+#define __ANGEL_H__
+
+//----------------------------------------------------------------------------
+// 
+// --- Include system headers ---
+//
+
+#include <cmath>
+#include <iostream>
+
+//  Define M_PI in the case it's not defined in the math header file
+#ifndef M_PI
+#  define M_PI  3.14159265358979323846
+#endif
+
+//----------------------------------------------------------------------------
+//
+// --- Include OpenGL header files and helpers ---
+//
+//   The location of these files vary by operating system.  We've included
+//     copies of open-soruce project headers in the "GL" directory local
+//     this this "include" directory.
+//
+
+#ifdef __APPLE__  // include Mac OS X verions of headers
+#  include <OpenGL/OpenGL.h>
+#  include <GLUT/glut.h>
+#else // non-Mac OS X operating systems
+#  include <GL/glew.h>
+#  include <GL/freeglut.h>
+#  include <GL/freeglut_ext.h>
+#endif  // __APPLE__
+
+// Define a helpful macro for handling offsets into buffer objects
+#define BUFFER_OFFSET( offset )   ((GLvoid*) (offset))
+
+//----------------------------------------------------------------------------
+//
+//  --- Include our class libraries and constants ---
+//
+
+namespace Angel {
+
+//  Helper function to load vertex and fragment shader files
+GLuint InitShader( const char* vertexShaderFile,
+		   const char* fragmentShaderFile );
+
+//  Defined constant for when numbers are too small to be used in the
+//    denominator of a division operation.  This is only used if the
+//    DEBUG macro is defined.
+const GLfloat  DivideByZeroTolerance = GLfloat(1.0e-07);
+
+//  Degrees-to-radians constant 
+const GLfloat  DegreesToRadians = M_PI / 180.0;
+
+}  // namespace Angel
+
+#include "vec.h"
+#include "mat.h"
+//#include "CheckError.h"
+
+// #define Print(x)  do { std::cerr << #x " = " << (x) << std::endl; } while(0)
+
+//  Globally use our namespace in our example programs.
+using namespace Angel;
+
+#endif // __ANGEL_H__

CheckError.h

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+//////////////////////////////////////////////////////////////////////////////
+//
+//  --- CheckError.h ---
+//
+//////////////////////////////////////////////////////////////////////////////
+
+#ifndef __CHECKERROR_H__
+#define __CHECKERROR_H__
+
+#include <stdio.h>
+//#include <GL/gl.h>
+#include <GLUT/glut.h>
+
+//----------------------------------------------------------------------------
+
+static const char*
+ErrorString( GLenum error )
+{
+    const char*  msg;
+    switch( error ) {
+#define Case( Token )  case Token: msg = #Token; break;
+	Case( GL_NO_ERROR );
+	Case( GL_INVALID_VALUE );
+	Case( GL_INVALID_ENUM );
+	Case( GL_INVALID_OPERATION );
+	Case( GL_STACK_OVERFLOW );
+	Case( GL_STACK_UNDERFLOW );
+	Case( GL_OUT_OF_MEMORY );
+#undef Case	
+    }
+
+    return msg;
+}
+
+//----------------------------------------------------------------------------
+
+static void
+_CheckError( const char* file, int line )
+{
+    GLenum  error = glGetError();
+
+    do {
+	fprintf( stderr, "[%s:%d] %s\n", file, line, ErrorString(error) );
+    } while ((error = glGetError()) != GL_NO_ERROR );
+
+}
+
+//----------------------------------------------------------------------------
+
+#define CheckError()  _CheckError( __FILE__, __LINE__ )
+
+//----------------------------------------------------------------------------
+
+#endif // !__CHECKERROR_H__

InitShader.cpp

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+
+#include "Angel.h"
+
+namespace Angel {
+
+// Create a NULL-terminated string by reading the provided file
+static char*
+readShaderSource(const char* shaderFile)
+{
+    FILE* fp = fopen(shaderFile, "r");
+
+    if ( fp == NULL ) { return NULL; }
+
+    fseek(fp, 0L, SEEK_END);
+    long size = ftell(fp);
+
+    fseek(fp, 0L, SEEK_SET);
+    char* buf = new char[size + 1];
+    fread(buf, 1, size, fp);
+
+    buf[size] = '\0';
+    fclose(fp);
+
+    return buf;
+}
+
+
+// Create a GLSL program object from vertex and fragment shader files
+GLuint
+InitShader(const char* vShaderFile, const char* fShaderFile)
+{
+    struct Shader {
+	const char*  filename;
+	GLenum       type;
+	GLchar*      source;
+    }  shaders[2] = {
+	{ vShaderFile, GL_VERTEX_SHADER, NULL },
+	{ fShaderFile, GL_FRAGMENT_SHADER, NULL }
+    };
+
+    GLuint program = glCreateProgram();
+
+    for ( int i = 0; i < 2; ++i ) {
+	Shader& s = shaders[i];
+	s.source = readShaderSource( s.filename );
+	if ( shaders[i].source == NULL ) {
+	    // std::cerr << "Failed to read " << s.filename << std::endl;
+	    exit( EXIT_FAILURE );
+	}
+
+	GLuint shader = glCreateShader( s.type );
+	glShaderSource( shader, 1, (const GLchar**) &s.source, NULL );
+	glCompileShader( shader );
+
+	GLint  compiled;
+	glGetShaderiv( shader, GL_COMPILE_STATUS, &compiled );
+	if ( !compiled ) {
+	    // std::cerr << s.filename << " failed to compile:" << std::endl;
+	    GLint  logSize;
+	    glGetShaderiv( shader, GL_INFO_LOG_LENGTH, &logSize );
+	    char* logMsg = new char[logSize];
+	    glGetShaderInfoLog( shader, logSize, NULL, logMsg );
+	    // std::cerr << logMsg << std::endl;
+	    delete [] logMsg;
+
+	    exit( EXIT_FAILURE );
+	}
+
+	delete [] s.source;
+
+	glAttachShader( program, shader );
+    }
+
+    /* link  and error check */
+    glLinkProgram(program);
+
+    GLint  linked;
+    glGetProgramiv( program, GL_LINK_STATUS, &linked );
+    if ( !linked ) {
+	// std::cerr << "Shader program failed to link" << std::endl;
+	GLint  logSize;
+	glGetProgramiv( program, GL_INFO_LOG_LENGTH, &logSize);
+	char* logMsg = new char[logSize];
+	glGetProgramInfoLog( program, logSize, NULL, logMsg );
+	// std::cerr << logMsg << std::endl;
+	delete [] logMsg;
+
+	exit( EXIT_FAILURE );
+    }
+
+    /* use program object */
+    glUseProgram(program);
+
+    return program;
+}
+
+}  // Close namespace Angel block