📄 tutorial_22.htm
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glBlendFunc(GL_ONE,GL_ONE);
glDepthFunc(GL_LEQUAL);
glEnable(GL_BLEND);
glBegin(GL_QUADS);
<font color="#ffffaa">// 前面</font>
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]=data[5*i+2];
c[1]=data[5*i+3];
c[2]=data[5*i+4];
SetUpBumps(n,c,l,s,t);
<font color="#ffffaa">// 设置纹理坐标为偏移后的纹理坐标</font>
glTexCoord2f(data[5*i]+c[0], data[5*i+1]+c[1]);
glVertex3f(data[5*i+2], data[5*i+3], data[5*i+4]);
}
<font color="#ffffaa">// 后面</font>
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]=data[5*i+2];
c[1]=data[5*i+3];
c[2]=data[5*i+4];
SetUpBumps(n,c,l,s,t);
glTexCoord2f(data[5*i]+c[0], data[5*i+1]+c[1]);
glVertex3f(data[5*i+2], data[5*i+3], data[5*i+4]);
}
<font color="#ffffaa">// 上面</font>
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]=data[5*i+2];
c[1]=data[5*i+3];
c[2]=data[5*i+4];
SetUpBumps(n,c,l,s,t);
glTexCoord2f(data[5*i]+c[0], data[5*i+1]+c[1]);
glVertex3f(data[5*i+2], data[5*i+3], data[5*i+4]);
}
<font color="#ffffaa">// 下面</font>
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]=data[5*i+2];
c[1]=data[5*i+3];
c[2]=data[5*i+4];
SetUpBumps(n,c,l,s,t);
glTexCoord2f(data[5*i]+c[0], data[5*i+1]+c[1]);
glVertex3f(data[5*i+2], data[5*i+3], data[5*i+4]);
}
<font color="#ffffaa">// 右面</font>
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]=data[5*i+2];
c[1]=data[5*i+3];
c[2]=data[5*i+4];
SetUpBumps(n,c,l,s,t);
glTexCoord2f(data[5*i]+c[0], data[5*i+1]+c[1]);
glVertex3f(data[5*i+2], data[5*i+3], data[5*i+4]);
}
<font color="#ffffaa">// 左面</font>
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]=data[5*i+2];
c[1]=data[5*i+3];
c[2]=data[5*i+4];
SetUpBumps(n,c,l,s,t);
glTexCoord2f(data[5*i]+c[0], data[5*i+1]+c[1]);
glVertex3f(data[5*i+2], data[5*i+3], data[5*i+4]);
}
glEnd();
</font></pre>
<table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_22_files/tl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_22_files/tc.png" height="28" width="100%"></td><td><img src="Tutorial_22_files/tr.png" height="28" width="28"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td background="Tutorial_22_files/l.png"><img src="Tutorial_22_files/l.png"></td>
<td valign="top" width="100%"><u>通道3:</u> <ul type="disc">
<li>使用颜色纹理Use (colored) base-texture</li>
<li>使用混合因子GL_DST_COLOR, GL_SRC_COLOR</li>
<li>这个混合等于把颜色值乘以2</li>
<li>使用光照</li>
<li>绘制几何体</li>
</ul>
这个过程将结束立方体的渲染，因为我们可以在是否使用多重渲染之间切换，所以必须把纹理环境参数设为GL_MODULATE，这是默认的值。</td>
<td background="Tutorial_22_files/r.png"><img src="Tutorial_22_files/r.png"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_22_files/bl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_22_files/bc.png" height="28" width="100%"></td><td><img src="Tutorial_22_files/br.png" height="28" width="28"></td></tr></tbody></table><font color="#aaffaa" size="3"><pre> if (!emboss) {
glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glBindTexture(GL_TEXTURE_2D,texture[filter]);
glBlendFunc(GL_DST_COLOR,GL_SRC_COLOR);
glEnable(GL_LIGHTING);
doCube();
}
</pre></font><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_22_files/tl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_22_files/tc.png" height="28" width="100%"></td><td><img src="Tutorial_22_files/tr.png" height="28" width="28"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td background="Tutorial_22_files/l.png"><img src="Tutorial_22_files/l.png"></td>
<td valign="top" width="100%"><u>最后的通道:</u> <ul type="disc">
<li>更新几何体</li>
<li>绘制标志</li>
</ul>
</td><td background="Tutorial_22_files/r.png"><img src="Tutorial_22_files/r.png"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_22_files/bl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_22_files/bc.png" height="28" width="100%"></td><td><img src="Tutorial_22_files/br.png" height="28" width="28"></td></tr></tbody></table><font color="#aaffaa" size="3">
<pre> 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;
<font color="#ffffaa">//绘制标志</font>
doLogo();
return true; <font color="#ffffaa">// 成功返回</font>
}
</pre>
</font><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_22_files/tl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_22_files/tc.png" height="28" width="100%"></td><td><img src="Tutorial_22_files/tr.png" height="28" width="28"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td background="Tutorial_22_files/l.png"><img src="Tutorial_22_files/l.png"></td>
<td valign="top" width="100%">这个函数将在多重纹理功能的支持下载两个通道中完成凹凸贴图的绘制，我们支持两个纹理单元，与一个纹理单元不同的是，我们给一个顶点设置两个纹理坐标。</td>
<td background="Tutorial_22_files/r.png"><img src="Tutorial_22_files/r.png"></td></tr></tbody></table><table border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><img src="Tutorial_22_files/bl.png" height="28" width="28"></td><td width="100%"><img src="Tutorial_22_files/bc.png" height="28" width="100%"></td><td><img src="Tutorial_22_files/br.png" height="28" width="28"></td></tr></tbody></table>
<font color="#aaffaa" size="3">
<pre>bool doMesh2TexelUnits(void) {
GLfloat c[4]={0.0f,0.0f,0.0f,1.0f}; <font color="#ffffaa">// 保存当前的顶点</font>
GLfloat n[4]={0.0f,0.0f,0.0f,1.0f}; <font color="#ffffaa">// 保存法线</font>
GLfloat s[4]={0.0f,0.0f,0.0f,1.0f}; <font color="#ffffaa">// s纹理坐标方向</font>
GLfloat t[4]={0.0f,0.0f,0.0f,1.0f}; <font color="#ffffaa">// t纹理坐标方向</font>
GLfloat l[4]; <font color="#ffffaa">// 保存灯光方向</font>
GLfloat Minv[16]; <font color="#ffffaa">// 保存模型变换矩阵的逆</font>
int i;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); <font color="#ffffaa">// 清空背景颜色和深度缓存</font>
<font color="#ffffaa">// 创建模型变换矩阵的逆</font>
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);
<font color="#ffffaa">// 设置灯光的位置</font>
l[0]=LightPosition[0];
l[1]=LightPosition[1];
l[2]=LightPosition[2];
l[3]=1.0f;
VMatMult(Minv,l);
</pre>
</font>
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