[迁移]opengl学习从头开始（笔记17 多重纹理 凹凸映射）
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2022-03-05 09:27:29
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/**
这里使用到的是opengl 和 glut 进行编写学习的笔记，一个简单的出口
使用到的开发库有 linux (gl glu glut) windows(opengl32.lib glu32.lib glut32.lib)
实现: 多重纹理，凹凸映射
看完代码应该意识到
g_texture 是图片Base.bmp加载进来的纹理
g_bump 是图片 Bump.bmp加载进来的纹理 r g b 为 原来的50%
g_invbmp 是通过 Bump.bmp 的每个像素 255 减获得的
原理
浮雕就是计算灯光和面法线之间的偏向获取纹理偏差，之后g_bump和g_invbump的纹理进行偏移
之后在进行混合绘制
glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
// 这个函数也是一个关键的点，自己网络上搜索下是如何使用的吧
//
//
这里使用的两种方式：
1 不使用多重纹理实现
2 使用多重纹理实现
例子：这里需要检测你的显卡是否支持GL_ARB_multitexture-support
它的作用是使你可以同时吧2个以上的不同纹理映射到opengl图元上
关键的几个函数，在里面进行小小的改动会出现一些不一样的东西^_^
setupbumps 这个是计算纹理的偏离量的
vmatmult 这个是把灯光的位置转换到对象坐标系中
键盘事件：
k 是否给浮雕贴上贴图
l 使用那种浮雕 这里有2中浮雕实现方式
h 切换是否使用浮雕效果
j 这个是用于切换查看3个纹理 g_texture g_bump g_invbump
是什么样子的
题外：
opengl的矩阵格式
0 4 8 12
1 5 9 13
2 6 10 14
3 7 11 15
问题：
*/
#include <iostream>
#include <GL/glut.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#ifdef _MSC_VER
#endif
#ifdef __GNUC__
#include <unistd.h>
#endif
using namespace std;
#define MAX_EMBOSS (GLfloat)0.01f // 突起最大值
#define MAX_EXTENSION_SPACE 10240 // 扩展字符串字符
#define MAX_EXTENSION_LENGHT 256 // 一个扩展的最大字符长度
bool g_emboss = false; // 这个是允许浮雕效果,还是使用颜色
bool g_bumps=true; // 开启凹凸纹理
bool g_multitextureSupported = false; // 判断是否支持我们要的扩展
bool g_useMultitexture = true; // 是否使用扩展
GLint g_maxTexelUnits = 1; //;
GLfloat xrot = 0.0f; // X Rotation
GLfloat yrot = 0.0f; // Y Rotation
GLfloat xspeed = 0.1f; // X Rotation Speed
GLfloat yspeed = 0.1f; // Y Rotation Speed
GLfloat z=-5.0f;
// 1 使用 g_texture 2 使用g_bump 3 使用 g_invbump
GLuint g_drawType = 0; // 这里使用绘制的方式，
GLuint g_texture; // 存储3张纹理
GLuint g_bump; // 3张凹凸纹理
GLuint g_invbump; // 凹纹理
GLuint g_glLogo; // opengl logo
GLuint g_multiLogo;
GLfloat g_LightAmbient[] = {0.2f, 0.2f, 0.2f}; // 环境光
GLfloat g_LightDiffuse[] = {1.0f, 1.0f, 1.0f}; // 漫反射
GLfloat g_LightPosition[] = {0.0f, 0.0f, 2.0f};
GLfloat g_Gray[] = { 0.5f, 0.5f, 0.5f, 1.0f};
// 下面的数据存储的是立方体的面，格式是2个纹理定点，3个坐标
//
GLfloat g_data[] = {
// front
0.0f, 0.0f, -1.0f, -1.0f, 1.0f,
1.0f, 0.0f, +1.0f, -1.0f, 1.0f,
1.0f, 1.0f, +1.0f, 1.0f, 1.0f,
0.0f, 1.0f, -1.0f, 1.0f, 1.0f,
// back
1.0f, 0.0f, -1.0f, -1.0f, -1.0f,
1.0f, 1.0f, -1.0f, 1.0f, -1.0f,
0.0f, 1.0f, 1.0f, 1.0f, -1.0f,
0.0f, 0.0f, 1.0f, -1.0f, -1.0f,
// top
0.0f, 1.0f, -1.0f, 1.0f, -1.0f,
0.0f, 0.0f, -1.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f, 1.0f,
1.0f, 1.0f, 1.0f, +1.0f, -1.0f,
// bottom
1.0f, 1.0f, -1.0f, -1.0f, -1.0f,
0.0f, 1.0f, 1.0f, -1.0f, -1.0f,
0.0f, 0.0f, 1.0f, -1.0f, 1.0f,
1.0f, 0.0f, -1.0f, -1.0f, 1.0f,
// right
1.0f,0.0f, 1.0f, -1.0f, -1.0f,
1.0f, 1.0f, 1.0f, 1.0f, -1.0f,
0.0f, 1.0f, 1.0f, 1.0f, 1.0f,
0.0f, 0.0f, 1.0f, -1.0f, 1.0f,
// left
0.0f, 0.0f, -1.0f, -1.0f, -1.0f,
1.0f, 0.0f, -1.0f, -1.0f, 1.0f,
1.0f, 1.0f, -1.0f, 1.0f, 1.0f,
0.0f, 1.0f, -1.0f, 1.0f, -1.0f
};
// 看到一个扩展是否在字符串中
bool isInString(char *string, const char *search)
{
int pos = 0;
int maxpos = strlen(search) - 1;
int len = strlen(string);
char *other;
for (int i = 0; i < len; i++)
{
if ((i == 0) || ((i > 1) && string[i-1] == '\n'))
{
other = &string[i];
pos = 0;
while (string[i] != '\n')
{
if (string[i] == search[pos]) pos++;
if ((pos > maxpos) && string[i+1] == '\n') return true;
i++;
}
}
}
return false;
}
// 初始化多重纹理
// 判断是否支持我们需要的扩展
bool initMultitexture(void)
{
char *extensions = strdup((char*)glGetString(GL_EXTENSIONS));
int len = strlen(extensions);
for (int i = 0; i < len; i++)
if (extensions[i] == ' ') extensions[i] = '\n';
#ifdef EXT_INFO
cout<<"supported GL extensions:\n"<<extensions<<endl;
#endif
if (isInString(extensions, "GL_ARB_mutitexture")
&& true
&& isInString(extensions, "GL_EXT_texture_env_combine"))
{
glGetIntegerv(GL_MAX_TEXTURE_UNITS_ARB,&g_maxTexelUnits);
cout<<"maxTexelUnits:"<<g_maxTexelUnits<<endl;
#ifdef EXT_INFO
cout<<"the GL_ARB_multitexture extension will be used."<<endl;
#endif
return true;
}
g_useMultitexture = false;
return false;
}
// 初始化
void initLight(void)
{
glLightfv(GL_LIGHT1, GL_AMBIENT, g_LightAmbient);
glLightfv(GL_LIGHT1, GL_DIFFUSE, g_LightDiffuse);
glLightfv(GL_LIGHT1, GL_POSITION, g_LightPosition);
glEnable(GL_LIGHT1);
}
// 图片的类型 包含宽 高 数据
struct Image
{
unsigned long sizeX;
unsigned long sizeY;
char *data;
};
typedef struct Image Image;
// 我们用来旋转下模型吧
float g_angle = 0;
////////////////////////////////
// 下面是读取自定义格式的模型信息文件使用的函数
//----------------------------------------------------------
// 读取图片文件
int ImageLoad(const char *filename, Image *image)
{
FILE *file;
unsigned long size; // 图片长度
unsigned long i; // 计数
unsigned short int planes;
unsigned short int bpp;
char temp; // bgr -rgb 变换
if ((file = fopen(filename, "rb")) == NULL)
{
printf("File Not Found: %s\n", filename);
return 0;
}
// 跳过文件的头部，准备读取宽度和高度
// 如果想自己具体的情况可以去看看bmp图片的相关信息
fseek(file, 18, SEEK_CUR);
// 读取宽度
if ((i = fread(&image->sizeX, 4, 1, file)) != 1)
{
printf("Error reading width from %s. \n", filename);
return 0;
}
printf("Width of %s: %lu\n", filename, image->sizeX);
// 读取宽度
if ((i = fread(&image->sizeY, 4, 1, file)) != 1)
{
printf("Error reading height from %s. \n", filename);
return 0;
}
printf("Height of %s: %lu\n", filename, image->sizeY);
// 计算长度(24bits或3bytes每个像素)
size = image->sizeX * image->sizeY * 3;
// 读取
if ((fread(&planes, 2, 1, file)) != 1)
{
printf("Error reading planes from %s. \n", filename);
return 0;
}
if (planes != 1)
{
printf("Planes from %s is not 1: %u\n", filename, planes);
return 0;
}
if ((i = fread(&bpp, 2, 1, file)) != 1)
{
printf("Error reading bpp from %s. \n", filename);
return 0;
}
if (bpp != 24)
{
printf("Bpp from %s is not 24: %u\n", filename, bpp);
return 0;
}
// 跳过余下的头文件数据
fseek(file, 24, SEEK_CUR);
// 读取数据
image->data = (char*) malloc (size);
if (image->data == NULL)
{
printf("Error allocating memory for color-corrected image data");
return 0;
}
if ((i = fread(image->data, size, 1, file)) != 1)
{
printf("Error reading image data from %s. \n", filename);
return 0;
}
// 交换颜色 bgr -> rgb
for (i = 0; i < size; i += 3)
{
temp = image->data[i];
image->data[i] = image->data[i+2];
image->data[i+2] = temp;
}
// 完成
return 1;
}
/**
* @brie 这里的目的是根据当前的顶点，法线和灯光计算出纹理的偏移量
* 这里的s t是表明当前纹理的uv的方向,比如前面的话就是 s(1,0,0) t(0,1,0)
* @param n 当前表面的法向量
* @param c 当点的定点坐标
* @param l 灯光的位置
* @param s s方向
* @param t t方向
*/
void setupbumps(GLfloat *n, GLfloat *c, GLfloat *l, GLfloat *s, GLfloat *t)
{
GLfloat v[3];
GLfloat lenq;
// 根据当前顶点坐标和灯光坐标计算出灯光当顶点坐标的向量v
v[0] = l[0] - c[0];
v[1] = l[1] - c[1];
v[2] = l[2] - c[2];
// 对v向量进行归一化
lenq = (GLfloat) sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]);
v[0] /= lenq;
v[1] /= lenq;
v[2] /= lenq;
// 把这里设置为0后看看效果有什么区别
// 计算出纹理的偏移量
c[0] = (s[0] * v[0] + s[1] * v[1] + s[2] * v[2]) * MAX_EMBOSS;
c[1] = (t[0] * v[0] + t[1] * v[1] + t[2] * v[2]) * MAX_EMBOSS;
//c[0] = 0;
//c[1] = 0;
}
// 读取 bitmaps 并转化成纹理
//void LoadGLTextures(const std::string& picname, GLuint& texture)
void LoadGLTextures1(const std::string& picname, GLuint& texture)
{
Image *image1;
image1 = (Image*) malloc (sizeof(Image));
if (image1 == NULL)
{
printf("Error allocating space for image");
exit(0);
}
if (!ImageLoad(picname.c_str(), image1))
exit(1);
// 创建纹理
// 线性滤波
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture); // 绑定2D纹理
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, 3, image1->sizeX, image1->sizeY,
0, GL_RGB, GL_UNSIGNED_BYTE, image1->data);
free(image1);
}
void loadGLTextures()
{
Image *image1;
image1 = (Image*) malloc (sizeof(Image));
if (image1 == NULL)
{
printf("Error allocating space for image");
exit(0);
}
if (!ImageLoad("Data/Base.bmp", image1))
exit(1);
// 创建纹理
glGenTextures(1, &g_texture);
// create nearest filtered texture
glBindTexture(GL_TEXTURE_2D, g_texture); // 绑定2D纹理
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, image1->sizeX, image1->sizeY,
0, GL_RGB, GL_UNSIGNED_BYTE, image1->data);
free(image1);
// bump
image1 = (Image*) malloc (sizeof(Image));
if (image1 == NULL)
{
printf("Error allocating space for image");
exit(0);
}
if (!ImageLoad("Data/Bump.bmp", image1))
exit(1);
// 创建纹理
glPixelTransferf(GL_RED_SCALE, 0.5f); // 改变成原来的50%
glPixelTransferf(GL_GREEN_SCALE, 0.5f);
glPixelTransferf(GL_BLUE_SCALE, 0.5f);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR,g_Gray);
glGenTextures(1, &g_bump);
// create nearest filtered texture
glBindTexture(GL_TEXTURE_2D, g_bump); // 绑定2D纹理
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, image1->sizeX, image1->sizeY,
0, GL_RGB, GL_UNSIGNED_BYTE, image1->data);
//
unsigned char * data = (unsigned char *)image1->data;
for (unsigned int i = 0; i < 3 * image1->sizeX * image1->sizeY; i++)
data[i] = 255 - data[i];
glGenTextures(1, &g_invbump);
// create nearest filtered texture
glBindTexture(GL_TEXTURE_2D, g_invbump); // 绑定2D纹理
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, image1->sizeX, image1->sizeY,
0, GL_RGB, GL_UNSIGNED_BYTE, image1->data);
glPixelTransferf(GL_RED_SCALE, 1.0f);
glPixelTransferf(GL_GREEN_SCALE, 1.0f);
glPixelTransferf(GL_BLUE_SCALE, 1.0f);
free(image1);
}
// 根据纹理和材质坐标绘制立方体
void doCube()
{
int i = 0;
glBegin(GL_QUADS);
// front
glNormal3f(0.0f, 0.0f, 1.0f);
for (i = 0; i < 4; i++)
{
glTexCoord2f(g_data[5*i], g_data[5*i + 1]);
glVertex3f(g_data[5*i + 2], g_data[5*i + 3], g_data[5 *i + 4]);
}
// back
glNormal3f(0.0f, 0.0f, -1.0f);
for (i = 4; i < 8; i++)
{
glTexCoord2f(g_data[5*i], g_data[5*i + 1]);
glVertex3f(g_data[5*i + 2], g_data[5*i + 3], g_data[5 *i + 4]);
}
// top
glNormal3f(0.0f, 1.0f, 0.0f);
for (i = 8; i < 12; i++)
{
glTexCoord2f(g_data[5*i], g_data[5*i + 1]);
glVertex3f(g_data[5*i + 2], g_data[5*i + 3], g_data[5 *i + 4]);
}
// bottom
glNormal3f(0.0f, -1.0f, 0.0f);
for (i = 12; i < 16; i++)
{
glTexCoord2f(g_data[5*i], g_data[5*i + 1]);
glVertex3f(g_data[5*i + 2], g_data[5*i + 3], g_data[5 *i + 4]);
}
// right
glNormal3f(-1.0f, 0.0f, 0.0f);
for (i = 16; i < 20; i++)
{
glTexCoord2f(g_data[5*i], g_data[5*i + 1]);
glVertex3f(g_data[5*i + 2], g_data[5*i + 3], g_data[5 *i + 4]);
}
// left
glNormal3f(1.0f, 0.0f, 0.0f);
for (i = 20; i < 24; i++)
{
glTexCoord2f(g_data[5*i], g_data[5*i + 1]);
glVertex3f(g_data[5*i + 2], g_data[5*i + 3], g_data[5 *i + 4]);
}
glEnd();
}
// 根据变化的矩阵计算在对象坐标系中灯光的位置
// v = vm, m is 4x4 v is 4dim row
/**
* @brief 这里是根据获取的变换的矩阵m和当前的当光坐标计算变换后灯光在对象坐标系中的位置坐标
* @param m 变换后的矩阵
* @param v 灯光坐标,计算后这个坐标将被设置
*
*/
void vmatmult(GLfloat *m, GLfloat *v)
{
GLfloat res[3];
res[0] = m[0] * v[0] + m[1] * v[1] + m[2] * v[2] + m[3] * v[3];
res[1] = m[4] * v[0] + m[5] * v[1] + m[6] * v[2] + m[7] * v[3];
res[2] = m[8] * v[0] + m[9] * v[1] + m[10] * v[2] + m[11] * v[3];
v[0] = res[0];
v[1] = res[1];
v[2] = res[2];
v[3] = m[15];
}
// 不使用多重纹理
// 使用方式1来进行凹凸映射
bool doMesh1TexelUnits(void)
{
GLfloat c[4]={0.0f,0.0f,0.0f,1.0f}; // 存储当前的坐标
GLfloat n[4]={0.0f,0.0f,0.0f,1.0f}; // 存储当前面的法向量
GLfloat s[4]={0.0f,0.0f,0.0f,1.0f}; // 纹理s的方向，归一化
GLfloat t[4]={0.0f,0.0f,0.0f,1.0f}; // 纹理t的方向，归一化
GLfloat l[4]; // 存储转换当对象空间的当光坐标
GLfloat Minv[16]; // 存储modelview的逆置矩阵
int i;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // 清楚颜色和深度缓
// Build Inverse Modelview Matrix First. This Substitutes One Push/Pop With One glLoadIdentity();
// Simply Build It By Doing All Transformations Negated And In Reverse Order.
// 首先创建modelview 的逆置矩阵， 它将代替push/pop 使用glloadidentity()
// 简单的创建这个是为了让我们可以容易控制变换的有效和无效(翻译是一个很悲剧的事情，大概意思就这样)
glLoadIdentity();
glRotatef(-yrot,0.0f,1.0f,0.0f);
glRotatef(-xrot,1.0f,0.0f,0.0f);
glTranslatef(0.0f,0.0f,-z);
glGetFloatv(GL_MODELVIEW_MATRIX,Minv);
glLoadIdentity();
glTranslatef(0.0f,0.0f,z);
glRotatef(xrot,1.0f,0.0f,0.0f);
glRotatef(yrot,0.0f,1.0f,0.0f);
// Transform The Lightposition Into Object Coordinates:
// 转换灯光坐标到对象坐标系
l[0]=g_LightPosition[0];
l[1]=g_LightPosition[1];
l[2]=g_LightPosition[2];
l[3]=1.0f; // Homogenous Coordinate
vmatmult(Minv,l);
/* PASS#1: Use Texture "Bump"
No Blend
No Lighting
No Offset Texture-Coordinates */
glBindTexture(GL_TEXTURE_2D, g_bump);
glDisable(GL_BLEND);
glDisable(GL_LIGHTING);
doCube();
/* PASS#2: Use Texture "Invbump"
Blend GL_ONE To GL_ONE
No Lighting
Offset Texture Coordinates
*/
glBindTexture(GL_TEXTURE_2D,g_invbump);
glBlendFunc(GL_ONE,GL_ONE);
glDepthFunc(GL_LEQUAL);
glEnable(GL_BLEND);
glBegin(GL_QUADS);
// Front Face
n[0]=0.0f; n[1]=0.0f; n[2]=1.0f;
s[0]=1.0f; s[1]=0.0f; s[2]=0.0f;
t[0]=0.0f; t[1]=1.0f; t[2]=0.0f;
for (i=0; i<4; i++) {
c[0]=g_data[5*i+2];
c[1]=g_data[5*i+3];
c[2]=g_data[5*i+4];
setupbumps(n,c,l,s,t);
glTexCoord2f(g_data[5*i]+c[0], g_data[5*i+1]+c[1]);
glVertex3f(g_data[5*i+2], g_data[5*i+3], g_data[5*i+4]);
}
// Back Face
n[0]=0.0f; n[1]=0.0f; n[2]=-1.0f;
s[0]=-1.0f; s[1]=0.0f; s[2]=0.0f;
t[0]=0.0f; t[1]=1.0f; t[2]=0.0f;
for (i=4; i<8; i++) {
c[0]=g_data[5*i+2];
c[1]=g_data[5*i+3];
c[2]=g_data[5*i+4];
setupbumps(n,c,l,s,t);
glTexCoord2f(g_data[5*i]+c[0], g_data[5*i+1]+c[1]);
glVertex3f(g_data[5*i+2], g_data[5*i+3], g_data[5*i+4]);
}
// Top Face
n[0]=0.0f; n[1]=1.0f; n[2]=0.0f;
s[0]=1.0f; s[1]=0.0f; s[2]=0.0f;
t[0]=0.0f; t[1]=0.0f; t[2]=-1.0f;
for (i=8; i<12; i++) {
c[0]=g_data[5*i+2];
c[1]=g_data[5*i+3];
c[2]=g_data[5*i+4];
setupbumps(n,c,l,s,t);
glTexCoord2f(g_data[5*i]+c[0], g_data[5*i+1]+c[1]);
glVertex3f(g_data[5*i+2], g_data[5*i+3], g_data[5*i+4]);
}
// Bottom Face
n[0]=0.0f; n[1]=-1.0f; n[2]=0.0f;
s[0]=-1.0f; s[1]=0.0f; s[2]=0.0f;
t[0]=0.0f; t[1]=0.0f; t[2]=-1.0f;
for (i=12; i<16; i++) {
c[0]=g_data[5*i+2];
c[1]=g_data[5*i+3];
c[2]=g_data[5*i+4];
setupbumps(n,c,l,s,t);
glTexCoord2f(g_data[5*i]+c[0], g_data[5*i+1]+c[1]);
glVertex3f(g_data[5*i+2], g_data[5*i+3], g_data[5*i+4]);
}
// Right Face
n[0]=1.0f; n[1]=0.0f; n[2]=0.0f;
s[0]=0.0f; s[1]=0.0f; s[2]=-1.0f;
t[0]=0.0f; t[1]=1.0f; t[2]=0.0f;
for (i=16; i<20; i++) {
c[0]=g_data[5*i+2];
c[1]=g_data[5*i+3];
c[2]=g_data[5*i+4];
setupbumps(n,c,l,s,t);
glTexCoord2f(g_data[5*i]+c[0], g_data[5*i+1]+c[1]);
glVertex3f(g_data[5*i+2], g_data[5*i+3], g_data[5*i+4]);
}
// Left Face
n[0]=-1.0f; n[1]=0.0f; n[2]=0.0f;
s[0]=0.0f; s[1]=0.0f; s[2]=1.0f;
t[0]=0.0f; t[1]=1.0f; t[2]=0.0f;
for (i=20; i<24; i++) {
c[0]=g_data[5*i+2];
c[1]=g_data[5*i+3];
c[2]=g_data[5*i+4];
setupbumps(n,c,l,s,t);
glTexCoord2f(g_data[5*i]+c[0], g_data[5*i+1]+c[1]);
glVertex3f(g_data[5*i+2], g_data[5*i+3], g_data[5*i+4]);
}
glEnd();
/* PASS#3: Use Texture "Base"
Blend GL_DST_COLOR To GL_SRC_COLOR (Multiplies By 2)
Lighting Enabled
No Offset Texture-Coordinates
*/
if (!g_emboss) {
glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glBindTexture(GL_TEXTURE_2D,g_texture);
glBlendFunc(GL_DST_COLOR,GL_SRC_COLOR);
glEnable(GL_LIGHTING);
doCube();
}
xrot+=xspeed;
yrot+=yspeed;
if (xrot>360.0f) xrot-=360.0f;
if (xrot<0.0f) xrot+=360.0f;
if (yrot>360.0f) yrot-=360.0f;
if (yrot<0.0f) yrot+=360.0f;
return true; // Keep Going
}
// 使用多重纹理
// 使用方式2来进行凹凸映射
bool doMesh2TexelUnits(void)
{
GLfloat c[4]={0.0f,0.0f,0.0f,1.0f}; // holds current vertex
GLfloat n[4]={0.0f,0.0f,0.0f,1.0f}; // normalized normal of current surface
GLfloat s[4]={0.0f,0.0f,0.0f,1.0f}; // s-texture coordinate direction, normalized
GLfloat t[4]={0.0f,0.0f,0.0f,1.0f}; // t-texture coordinate direction, normalized
GLfloat l[4]; // holds our lightposition to be transformed into object space
GLfloat Minv[16]; // holds the inverted modelview matrix to do so.
int i;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer
// Build Inverse Modelview Matrix First. This Substitutes One Push/Pop With One glLoadIdentity();
// Simply Build It By Doing All Transformations Negated And In Reverse Order.
glLoadIdentity();
glRotatef(-yrot,0.0f,1.0f,0.0f);
glRotatef(-xrot,1.0f,0.0f,0.0f);
glTranslatef(0.0f,0.0f,-z);
glGetFloatv(GL_MODELVIEW_MATRIX,Minv);
glLoadIdentity();
glTranslatef(0.0f,0.0f,z);
glRotatef(xrot,1.0f,0.0f,0.0f);
glRotatef(yrot,0.0f,1.0f,0.0f);
// Transform The Lightposition Into Object Coordinates:
l[0]=g_LightPosition[0];
l[1]=g_LightPosition[1];
l[2]=g_LightPosition[2];
l[3]=1.0f; // Homogenous Coordinate
vmatmult(Minv,l);
/* PASS#1: Texel-Unit 0: Use Texture "Bump"
No Blend
No Lighting
No Offset Texture-Coordinates
Texture-Operation "Replace"
Texel-Unit 1: Use Texture "Invbump"
No Lighting
Offset Texture Coordinates
Texture-Operation "Replace"
*/
// TEXTURE-UNIT #0
glActiveTextureARB(GL_TEXTURE0_ARB);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, g_bump);
glTexEnvf(GL_TEXTURE_ENV, (GLenum)GL_TEXTURE_ENV_MODE, GL_COMBINE_EXT);
glTexEnvf(GL_TEXTURE_ENV, (GLenum)GL_COMBINE_RGB_EXT, GL_REPLACE);
// TEXTURE-UNIT #1:
glActiveTextureARB(GL_TEXTURE1_ARB);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, g_invbump);
glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_EXT);
glTexEnvf (GL_TEXTURE_ENV, (GLenum)GL_COMBINE_RGB_EXT, GL_ADD);
// General Switches:
glDisable(GL_BLEND);
glDisable(GL_LIGHTING);
glBegin(GL_QUADS);
// Front Face
n[0]=0.0f; n[1]=0.0f; n[2]=1.0f;
s[0]=1.0f; s[1]=0.0f; s[2]=0.0f;
t[0]=0.0f; t[1]=1.0f; t[2]=0.0f;
for (i=0; i<4; i++) {
c[0]=g_data[5*i+2];
c[1]=g_data[5*i+3];
c[2]=g_data[5*i+4];
setupbumps(n,c,l,s,t);
glMultiTexCoord2fARB(GL_TEXTURE0_ARB,g_data[5*i] , g_data[5*i+1]);
glMultiTexCoord2fARB(GL_TEXTURE1_ARB,g_data[5*i]+c[0], g_data[5*i+1]+c[1]);
glVertex3f(g_data[5*i+2], g_data[5*i+3], g_data[5*i+4]);
}
// Back Face
n[0]=0.0f; n[1]=0.0f; n[2]=-1.0f;
s[0]=-1.0f; s[1]=0.0f; s[2]=0.0f;
t[0]=0.0f; t[1]=1.0f; t[2]=0.0f;
for (i=4; i<8; i++) {
c[0]=g_data[5*i+2];
c[1]=g_data[5*i+3];
c[2]=g_data[5*i+4];
setupbumps(n,c,l,s,t);
glMultiTexCoord2fARB(GL_TEXTURE0_ARB,g_data[5*i] , g_data[5*i+1]);
glMultiTexCoord2fARB(GL_TEXTURE1_ARB,g_data[5*i]+c[0], g_data[5*i+1]+c[1]);
glVertex3f(g_data[5*i+2], g_data[5*i+3], g_data[5*i+4]);
}
// Top Face
n[0]=0.0f; n[1]=1.0f; n[2]=0.0f;
s[0]=1.0f; s[1]=0.0f; s[2]=0.0f;
t[0]=0.0f; t[1]=0.0f; t[2]=-1.0f;
for (i=8; i<12; i++) {
c[0]=g_data[5*i+2];
c[1]=g_data[5*i+3];
c[2]=g_data[5*i+4];
setupbumps(n,c,l,s,t);
glMultiTexCoord2fARB(GL_TEXTURE0_ARB,g_data[5*i] , g_data[5*i+1] );
glMultiTexCoord2fARB(GL_TEXTURE1_ARB,g_data[5*i]+c[0], g_data[5*i+1]+c[1]);
glVertex3f(g_data[5*i+2], g_data[5*i+3], g_data[5*i+4]);
}
// Bottom Face
n[0]=0.0f; n[1]=-1.0f; n[2]=0.0f;
s[0]=-1.0f; s[1]=0.0f; s[2]=0.0f;
t[0]=0.0f; t[1]=0.0f; t[2]=-1.0f;
for (i=12; i<16; i++) {
c[0]=g_data[5*i+2];
c[1]=g_data[5*i+3];
c[2]=g_data[5*i+4];
setupbumps(n,c,l,s,t);
glMultiTexCoord2fARB(GL_TEXTURE0_ARB,g_data[5*i] , g_data[5*i+1] );
glMultiTexCoord2fARB(GL_TEXTURE1_ARB,g_data[5*i]+c[0], g_data[5*i+1]+c[1]);
glVertex3f(g_data[5*i+2], g_data[5*i+3], g_data[5*i+4]);
}
// Right Face
n[0]=1.0f; n[1]=0.0f; n[2]=0.0f;
s[0]=0.0f; s[1]=0.0f; s[2]=-1.0f;
t[0]=0.0f; t[1]=1.0f; t[2]=0.0f;
for (i=16; i<20; i++) {
c[0]=g_data[5*i+2];
c[1]=g_data[5*i+3];
c[2]=g_data[5*i+4];
setupbumps(n,c,l,s,t);
glMultiTexCoord2fARB(GL_TEXTURE0_ARB,g_data[5*i] , g_data[5*i+1] );
glMultiTexCoord2fARB(GL_TEXTURE1_ARB,g_data[5*i]+c[0], g_data[5*i+1]+c[1]);
glVertex3f(g_data[5*i+2], g_data[5*i+3], g_data[5*i+4]);
}
// Left Face
n[0]=-1.0f; n[1]=0.0f; n[2]=0.0f;
s[0]=0.0f; s[1]=0.0f; s[2]=1.0f;
t[0]=0.0f; t[1]=1.0f; t[2]=0.0f;
for (i=20; i<24; i++) {
c[0]=g_data[5*i+2];
c[1]=g_data[5*i+3];
c[2]=g_data[5*i+4];
setupbumps(n,c,l,s,t);
glMultiTexCoord2fARB(GL_TEXTURE0_ARB,g_data[5*i] , g_data[5*i+1] );
glMultiTexCoord2fARB(GL_TEXTURE1_ARB,g_data[5*i]+c[0], g_data[5*i+1]+c[1]);
glVertex3f(g_data[5*i+2], g_data[5*i+3], g_data[5*i+4]);
}
glEnd();
// 第2部分
// 使用基本纹理Base.bmp
// 使用GL_DST_COLOR ,GL_SRC_COLOR进行混合
// 开启灯光
// 不偏移纹理坐标
glActiveTextureARB(GL_TEXTURE1_ARB);
glDisable(GL_TEXTURE_2D);
glActiveTextureARB(GL_TEXTURE0_ARB);
if (!g_emboss) {
glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glBindTexture(GL_TEXTURE_2D,g_texture);
glBlendFunc(GL_DST_COLOR,GL_SRC_COLOR);
glEnable(GL_BLEND);
glEnable(GL_LIGHTING);
doCube();
}
xrot+=xspeed;
yrot+=yspeed;
if (xrot>360.0f) xrot-=360.0f;
if (xrot<0.0f) xrot+=360.0f;
if (yrot>360.0f) yrot-=360.0f;
if (yrot<0.0f) yrot+=360.0f;
return true; // Keep Going
}
// 这个是不使用要图映射的
bool doMeshNoBumps(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer
glLoadIdentity(); // Reset The View
glTranslatef(0.0f,0.0f,z);
glRotatef(xrot,1.0f,0.0f,0.0f);
glRotatef(yrot,0.0f,1.0f,0.0f);
if (g_useMultitexture) {
glActiveTextureARB(GL_TEXTURE1_ARB);
glDisable(GL_TEXTURE_2D);
glActiveTextureARB(GL_TEXTURE0_ARB);
}
glDisable(GL_BLEND);
switch (g_drawType)
{
case 1:
glBindTexture(GL_TEXTURE_2D,g_texture);
break;
case 2:
glBindTexture(GL_TEXTURE_2D,g_bump);
break;
case 3:
glBindTexture(GL_TEXTURE_2D,g_invbump);
break;
}
glBlendFunc(GL_DST_COLOR,GL_SRC_COLOR);
glEnable(GL_LIGHTING);
doCube();
xrot+=xspeed;
yrot+=yspeed;
if (xrot>360.0f) xrot-=360.0f;
if (xrot<0.0f) xrot+=360.0f;
if (yrot>360.0f) yrot-=360.0f;
if (yrot<0.0f) yrot+=360.0f;
return true; // Keep Going
}
//===========================OpenGL 部分=========================
// 初始化opengl的一些参数
void init()
{
g_multitextureSupported = initMultitexture();
loadGLTextures();
glEnable(GL_TEXTURE_2D);
glShadeModel(GL_SMOOTH);
glClearColor(0.0f, 0.0f, 0.0f, 0.5f); // 清理背景颜色为蓝色
glClearDepth(1.0);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
initLight();
}
//------------------------------------
// 设置刷新时间
void timer(int p)
{
glutPostRedisplay();
glutTimerFunc(20, timer, 0);
}
//-----------------------------------
// 显示我们要绘制的模型
void display()
{
if (g_bumps) {
if (g_useMultitexture && g_maxTexelUnits>1)
doMesh2TexelUnits();
else
doMesh1TexelUnits();
}
else
{
doMeshNoBumps();
}
glutSwapBuffers(); //双缓冲
}
//-----------------------------------
// 当窗口变化的时候会调用这里
void reshape(int w, int h)
{
/* 视口设置
* 这个是当窗口发生大小变化的时候会调用这里，大家可以自己
* 拉伸下窗口就可以看到不一样的地方了
*/
glViewport(0, 0, (GLsizei) w, (GLsizei) h); // 设置视口
glMatrixMode(GL_PROJECTION); // 设置当前矩阵为投影矩阵
glLoadIdentity();
if (h == 0) h = 1; // 防止除0情况
gluPerspective(45.0f,(GLfloat) w / (GLfloat)h , 0.5f, -1000.0f);
glMatrixMode(GL_MODELVIEW); // 设置当前矩阵为模型矩阵
glLoadIdentity();
}
//-----------------------------------
//键盘事件
void keyboard(unsigned char key, int x, int y)
{
cout<<"key="<<key<<endl;
switch (key)
{
case 27: // 当按下键盘的esc键的时候退出
exit(0);
break;
case 'j':
case 'J': // 看当前的3中纹理分别是什么样子的 g_texture g_bump g_invbump
g_drawType++;
if (g_drawType > 3) g_drawType = 1;
break;
case 'k':
case 'K': // 是否贴上纹理
g_emboss = !g_emboss;
break;
case 'l':
case 'L': // 使用两种浮雕的那一种
g_useMultitexture = ((!g_useMultitexture) && g_multitextureSupported);
break;
case 'H':
case 'h': // 判断是否使用浮雕效果
g_bumps = !g_bumps;
break;
}
}
//------------------------------------
// 鼠标鼠标事件·
void MouseEvent(int button, int state, int x, int y)
{
}
//-------------------------------------
// 鼠标移动事件
void MotionMove(int x,int y)
{
}
int main(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH);
glutInitWindowPosition(100, 100);
glutInitWindowSize(800, 600);
glutCreateWindow("OpenGLDemo");
init();
glutTimerFunc(20,timer,0); // 设置更新时间
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutMouseFunc(MouseEvent);
glutMotionFunc(MotionMove);
glutMainLoop();
return 0;
}
// makefile 使用笔记1的
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