OpenGL startup V3.0

Design goals

Components

Example file structure

Physical Structure

1. init_glut
2. set glut callbacks
3. init GL (load extensions, print some basic info)
4. init antTweakBar
5. call initApp() - calls custom function defined in app.cpp file
6. call glutMainLoop()
7. call cleanUp() - cunstom function defined in app.cpp file
8. cleanup additional libs like antTweakBar

GLUT callbacks:
callbacks are used to process basic events (like for antTweakBar) and they call custom code defined in app.cpp file.

// window:
void mainChangeSize(int w, int h);

// mouse:
void mainProcessMouse(int button, int state, int x, int y);
void mainProcessMouseMotion(int x, int y);
void mainProcessMousePassiveMotion(int x, int y);

mainIdle
updates the timer, calculates fps, calls updateScene and renderScene custom functions

{
    double deltaTime;
    utils::updateTimer(&deltaTime, &Globals::sAppTime);

    utils::calculateFps(&Globals::sFps);

    updateScene(deltaTime);

    renderScene();

    TwDraw();
    glutSwapBuffers();
}

Custom code
This is defined in app.cpp file, contains code specific for the particular application.

// init textures, camera, shaders, etc, etc
bool initApp()

void cleanUp();

// window:
void changeSize(int w, int h);

// keyboard:
void processNormalKeys(unsigned char key, int x, int y);
void pressSpecialKey(int key, int x, int y);
void releaseSpecialKey(int key, int x, int y);

// mouse:
void processMouse(int button, int state, int x, int y);
void processMouseMotion(int x, int y);
void processMousePassiveMotion(int x, int y);

// update & rendering (called from mainIdle())
void updateScene(double deltaTime);
void renderScene();

Example Code

// shader loading
ShaderProgram gStripesProgram; // declared as global (not nice!)
shaderUtils::loadAndBuildShaderPairFromFile(&gStripesProgram, 
                                            "shaders/stripes.vs", 
                                            "shaders/stripes.fs");

// transformations & camera (declared as globals)
glm::vec3 gCamPos;
glm::mat4 gModelViewMatrix;
glm::mat4 gProjectionMatrix;

// in renderScene:
gModelViewMatrix = glm::lookAt(gCamPos, glm::vec3(0.0f, 0.0f, gCamPos[2]-2), 
                               glm::vec3(0.0f, 1.0f, 0.0f));

// shader setup:
gStripesProgram.use();

gStripesProgram.uniform1f("animParam", gAnimParam);
gStripesProgram.uniform1i("texture0", 0);
gStripesProgram.uniformMatrix4f("projectionMatrix", 
                                glm::value_ptr(gProjectionMatrix));
gStripesProgram.uniformMatrix4f("modelviewMatrix",  
                                glm::value_ptr(gModelViewMatrix));

// Tweak:
TwAddVarRW(Globals::sMainTweakBar, "camera Z", TW_TYPE_FLOAT, 
&gCamPos[2], "min=0.0 max=12.0 step=0.1");

Screens

Links