OpenGL 入门教程 模型视图投影矩阵 变换光线

// SphereWorld.cpp
// OpenGL SuperBible
// New and improved (performance) sphere world
// Program by Richard S. Wright Jr.

#include <GLTools.h>
#include <GLShaderManager.h>
#include <GLFrustum.h>
#include <GLBatch.h>
#include <GLMatrixStack.h>
#include <GLGeometryTransform.h>
#include <StopWatch.h>

#include <math.h>
#include <stdio.h>

#ifdef __APPLE__
#include <glut/glut.h>
#else
#define FREEGLUT_STATIC
#include <GL/glut.h>
#endif


GLShaderManager		shaderManager;			// Shader Manager
GLMatrixStack		modelViewMatrix;		// Modelview Matrix
GLMatrixStack		projectionMatrix;		// Projection Matrix
GLFrustum			viewFrustum;		// View Frustum 用来构造投影矩阵
GLGeometryTransform	transformPipeline;		// Geometry Transform Pipeline

GLTriangleBatch		torusBatch;
GLBatch				floorBatch;


//////////////////////////////////////////////////////////////////
// This function does any needed initialization on the rendering
// context. 
void SetupRC()
{
	// Initialze Shader Manager
	shaderManager.InitializeStockShaders();

	glEnable(GL_DEPTH_TEST);
	glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

	// This makes a torus
	gltMakeTorus(torusBatch, 0.4f, 0.15f, 30, 30);


	floorBatch.Begin(GL_LINES, 324);
	for (GLfloat x = -20.0; x <= 20.0f; x += 0.5) {
		floorBatch.Vertex3f(x, -0.55f, 20.0f);//画模型视图投影矩阵的|线
		floorBatch.Vertex3f(x, -0.55f, -20.0f);

		floorBatch.Vertex3f(20.0f, -0.55f, x);//画模型视图投影矩阵的-线
		floorBatch.Vertex3f(-20.0f, -0.55f, x);
	}
	floorBatch.End();
}


///////////////////////////////////////////////////
// Screen changes size or is initialized
void ChangeSize(int nWidth, int nHeight)
{
	glViewport(0, 0, nWidth, nHeight);
	//创建模型视图投影矩阵

	// Create the projection matrix, and load it on the projection matrix stack
	viewFrustum.SetPerspective(35.0f, float(nWidth) / float(nHeight), 1.0f, 100.0f);
	projectionMatrix.LoadMatrix(viewFrustum.GetProjectionMatrix());

	//变换管线
	// Set the transformation pipeline to use the two matrix stacks 
	transformPipeline.SetMatrixStacks(modelViewMatrix, projectionMatrix);
}


// Called to draw scene
void RenderScene(void)
{
	// Color values
	static GLfloat vFloorColor[] = { 0.0f, 1.0f, 0.0f, 1.0f };
	static GLfloat vTorusColor[] = { 1.0f, 0.0f, 0.0f, 1.0f };

	// Time Based animation
	static CStopWatch	rotTimer;
	float yRot = rotTimer.GetElapsedSeconds() * 60.0f;

	// Clear the color and depth buffers
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);


	// Save the current modelview matrix (the identity matrix)
	modelViewMatrix.PushMatrix();

	// Draw the ground
	shaderManager.UseStockShader(GLT_SHADER_FLAT,
		transformPipeline.GetModelViewProjectionMatrix(),
		vFloorColor);
	floorBatch.Draw();

	// Draw the spinning Torus
	modelViewMatrix.Translate(0.0f, 0.0f, -2.5f);
	modelViewMatrix.Rotate(yRot, 0.0f, 1.0f, 0.0f);
	shaderManager.UseStockShader(GLT_SHADER_FLAT, transformPipeline.GetModelViewProjectionMatrix(),
		vTorusColor);
	torusBatch.Draw();

	// Restore the previous modleview matrix (the idenity matrix)
	modelViewMatrix.PopMatrix();

	// Do the buffer Swap
	glutSwapBuffers();

	// Tell GLUT to do it again
	glutPostRedisplay();
}


int main(int argc, char* argv[])
{
	gltSetWorkingDirectory(argv[0]);

	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
	glutInitWindowSize(800, 600);

	glutCreateWindow("OpenGL SphereWorld");

	glutReshapeFunc(ChangeSize);
	glutDisplayFunc(RenderScene);

	GLenum err = glewInit();
	if (GLEW_OK != err) {
		fprintf(stderr, "GLEW Error: %s\n", glewGetErrorString(err));
		return 1;
	}


	SetupRC();
	glutMainLoop();
	return 0;
}