I cannot get the source code from Chapter 2 “Triangles” to work. It renders the background, but the triangle is not rendered. It seems to have something to do with triangleBatch, because when I move the triangle assignment lines to directly above the trianglebatch.draw, everything works. Since triangleBatch is a global variable, I don’t understand why this code doesn’t work. This is the exact same source as found in the book.
I’ve attached the source below.
#include <GLTools.h>
#include <GLShaderManager.h>
#include <iostream>
#ifdef __APPLE__
#include <glut/glut.h>
#else
#define FREEGLUT_STATIC
#include <GL/glut.h>
#endif
using namespace std;
GLBatch triangleBatch;
GLShaderManager shaderManager;
char test[] = "TEST";
void ChangeSize(int w, int h)
{
glViewport(0,0,w,h);
}
void SetupRC()
{
cout << "SetupRC" << endl;
glClearColor(0.0f,0.0f,1.0f,1.0f);
shaderManager.InitializeStockShaders();
GLfloat vVerts[] = {-0.5f,0.0f,0.0f,0.5f,0.0f,0.0f,0.0f,0.5f,0.0f};
triangleBatch.Begin(GL_TRIANGLES, 3);
triangleBatch.CopyVertexData3f(vVerts);
triangleBatch.End();
std::cout << "SetupRC....Complete" << endl;
cout << test << endl;
}
void RenderScene(void)
{
std::cout << "RenderScene
";
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
GLfloat vRed[] = {1.0f,0.0f,0.0f,1.0f};
shaderManager.UseStockShader(GLT_SHADER_IDENTITY, vRed);
triangleBatch.Draw();
glutSwapBuffers();
}
int main(int argc, char* argv[])
{
gltSetWorkingDirectory(argv[0]);
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH | GLUT_STENCIL);
glutInitWindowSize(800, 600);
glutCreateWindow("Triangle");
glutReshapeFunc(ChangeSize);
glutDisplayFunc(RenderScene);
GLenum err= glewInit();
if(GLEW_OK != err){
fprintf(stderr, "GLEW Error: %s
", glewGetErrorString(err));
return 1;
}
SetupRC();
glutMainLoop();
return 0;
}
Yeah, I can’t imagine it being a compiler setting, but I just don’t know. I tested the globals with that “std::string test” variable. It works as expected. Although it seems like triangleBatch variable is acting local when it is indeed global. Like I said, everything works like it’s suppose to, but only if triangleBatch is declared locally.