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
4000
);
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;
}