Implementation
MultiColorCube class is implemented as below to draw the single colored cube.
It's located in VOGLLib\Geometry\Cube\MultiColorCube.h.
//Implements multi colored cube
class MultiColoredCube :public BaseGeometry
{
public:
//OpenGL initialization
void Init()
{
//initialize opengl context
BaseGeometry::Init(new CubeMesh());
//generate vbo data
kount = mesh->GenerateVerticesData(false, VAOUtil::POS | VAOUtil::CLR, vaoutl);
//setup vertices
vaoutl.SetupVBO(0, VAOUtil::POS);
vaoutl.SetupVBO(1, VAOUtil::CLR);
vaoutl.unbindVAO();
}
//override
virtual string vertexShaderSource()
{
return R"(
#version 330 core
layout (location = 0) in vec3 vVertex;
layout (location = 1) in vec3 vColor;
out vec3 fcolor;
uniform mat4 transform;
void main()
{
gl_Position = transform * vec4(vVertex, 1.0);
fcolor = vColor;
};
)";
}
//override
virtual string fragmentShaderSource()
{
return R"(
#version 330 core
in vec3 fcolor;
out vec4 FragColor;
void main()
{
FragColor = vec4(fcolor,1.0);
};
)";
}
};
Lesson05 Project
This purpose of this Lesson05 project is to create a Window initialized with OpenGL context and draw a MultiColorCube with 6 colors one for each face.
As discussed in introduction create tutorial lesson project Lesson02 under Lessons folder.
Add a header file Scene.h as shown below. The class itself is self explanatory.
The WM_CLOSE event is handled in OnCloseWindow function and the window is destroyed and application is shutdown.
The Init method calls BaseScene's Init to create hosting window and OpenGL Context. It also attaches BaseCameraInputHandler to rotate the cube either by keyboard or mouse inputs.
The DrawScene method draws the cube with multiple colors and rotates as per keyboard or mouse inputs.
The Cleanup method release the resources.
The Scene class is implemented as below. It's located in Lessons\Lesson05\Scene.h file.
#include "Scene\BaseScene.h"
#include "Geometry\Cube\MultiColoredCube.h"
class Scene:public BaseScene
{
public:
//message handler
BEGIN_MSG_MAP(Scene0)
MESSAGE_HANDLER(WM_CLOSE, OnCloseWindow)
CHAIN_MSG_MAP(BaseScene)
END_MSG_MAP()
//override
int Init(RECT rect, WCHAR *windowname)
{
//create host window and context
BaseScene::Init(rect, windowname);
//attach mouse keyboard input handler
mskbd = new BaseCameraInputHandler(m_hWnd);
//Create multicolor cube
cube.Init();
return 0;
}
//release resources
void Cleanup()
{
cube.Cleanup();
delete mskbd;
}
//draw the scene
void DrawScene()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//get model view projection matrix.
//only model is modified
//view and projection will be identity matrix
mskbd->fetchCameraData(&cube.camera);
cube.Draw();
}
//Close the window
LRESULT OnCloseWindow(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled)
{
bHandled = TRUE;
DestroyWindow();
PostQuitMessage(0);
return 0;
}
private:
MultiColoredCube cube;
};
The main.cpp is located in Lessons\Lesson05\main.cpp file. It creates the scene object and calls its init method.
#include "Scene.h"
Scene scene;
int WINAPI WinMain(HINSTANCE inst, HINSTANCE prev, LPSTR cmd_line, int show)
{
scene.Init(RECT{ 100, 100, 780, 500 }, L"Modern OpenGL-Tutorial - Lesson05");
scene.ShowWindow(show);
MSG msg;
while (GetMessage(&msg, 0, 0, 0))
{
TranslateMessage(&msg);
DispatchMessageA(&msg);
}
return 0;
}
The output looks as shown in the top. The cube is rotated by 20 degrees pitch and 20 degrees yaw. The camera position at the origin looking down on -Z axis or the back face of the cube.
To rotate the cube X,Y and Z keys can be used. They rotate respectively pitch, yaw and roll the cube by 10 degrees.
In the next post we shall learn essential 3d Math.
