2、创建纹理
GLuint OpenGLOperate::createTexture(QString nFile)
{
GLuint textureId = 0;
QFile file(nFile);
if (!file.exists())
return 0;
QImage p_w_picpath(nFile);
QImage textureImage;
int width = p_w_picpath.width();
int height = p_w_picpath.height();
textureImage = p_w_picpath.convertToFormat(QImage::Format_RGBA8888);
textureImage = textureImage.mirrored();
m_OpenGLCore->glGenTextures(1, &textureId);
m_OpenGLCore->glBindTexture(GL_TEXTURE_2D, textureId);
m_OpenGLCore->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
m_OpenGLCore->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
m_OpenGLCore->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
m_OpenGLCore->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
m_OpenGLCore->glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, \
GL_RGBA, GL_UNSIGNED_BYTE, textureImage.bits());
m_OpenGLCore->glBindTexture(GL_TEXTURE_2D, 0);
return textureId;
}为Shader的纹理赋值，默认使用0号纹理单元
m_Texture = m_OpenGLOperate->createTexture(":/niutou.bmp");
OpenGLCore->glBindTexture(GL_TEXTURE_2D, m_Texture);
OpenGLCore->glUniform1i(m_TextureLocation, 0);3、关于环境光、漫反射及高光
环境光：在无光源下的环境的亮度；这里将环境光直接写到fragment shader中（也可以在用uniform在CPU上设置）
设置环境光的亮度及材质
// Ambient
vec4 M_AmbientLightColor = vec4(0.2, 0.2, 0.2, 1.0);
vec4 M_AmbientMaterial = vec4(0.2, 0.2, 0.2, 1.0);
vec4 ambientColor = M_AmbientLightColor * M_AmbientMaterial;
漫反射：在光的照射下物体反射的颜色，也就是物体反射的颜色
光照强度的计算：物体表面的点指向光源的向量 点乘 法线，就是发光强度。
分析：指向光源的向量与法线的夹角为0度时，反射的光线越多，发光强度越大。夹角为90度时，发光强度就为0，如果大于90度则为背光面。
// Diffuse
vec3 M_LightPos = vec3(10.0, 10.0, 0.0);
vec3 LightNormal = normalize(M_LightPos); // 指向光源的单位向量，方向光
vec3 NormalNormal = normalize(M_normal); // 法线的单位向量
// 点乘获取光照强度
vec4 M_DiffuseLightColor = vec4(1.0, 1.0, 1.0, 1.0);
vec4 M_DiffuseMaterial = vec4(0.9, 0.9, 0.9, 1.0);
vec4 diffuseColor = M_DiffuseLightColor * M_DiffuseMaterial *
max(0.0, dot(NormalNormal, LightNormal));
镜面发射：高光，在金属等物体表面的光
标准phong模型 光照强度的计算：反射光线 点乘 直线眼睛的向量作为基底，然后取一个幂
分析：当反射光线与指向眼睛的向量夹角为0度时，则为最亮的部分
// 镜面反射
vec4 specularLightColor = vec4(1.0, 1.0, 1.0, 1.0);
vec4 specularMaterial = vec4(0.4, 0.4, 0.4, 1.0);
vec3 reflerDir = normalize(reflect(-LightNormal, NormalNormal));
vec3 eyeDir = normalize(vec3(0.0) - M_WordPos);
vec4 specularColor = specularLightColor * specularMaterial *
pow(max(0.0, dot(reflerDir, eyeDir)), 180);
4、法线矩阵（Normal Matrix）
当模型矩阵变换时，法线也会变，需要重新计算法线，公式为：
法线矩阵 = 模型矩阵的逆的转置
变换后的法线 = 法线矩阵 * 法线
QMatrix4x4 nMormalMat; // 法线矩阵
QMatrix4x4 nModeMat; // 模型矩阵
nModeMat.translate(0, -50, -200);
if (m_Rote > 360)
m_Rote = 0;
else
m_Rote += 1.0f;
nModeMat.rotate(m_Rote, 0.0f, 1.0f, 0.0f);
QMatrix4x4 nNormalMatrix = nModeMat.inverted().transposed();
Vertex Shader:
attribute vec3 pos;
attribute vec2 coord;
attribute vec3 normal;
uniform mat4 M;
uniform mat4 V;
uniform mat4 P;
uniform mat4 NM;
varying vec2 M_coord;
varying vec3 M_normal;
varying vec3 M_WordPos;
void main()
{
M_coord = coord;
M_WordPos = vec3(M * vec4(pos, 1.0));
M_normal = mat3(NM) * normal;// 计算法线
gl_Position = P * V * M * vec4(pos, 1.0);
}Fragment Shader
uniform sampler2D U_MainTexture;
varying vec2 M_coord;
varying vec3 M_normal;
varying vec3 M_WordPos;
//uniform vec3 M_LightPos; // 平行光
//uniform vec4 M_AmbientLightColor;
//uniform vec4 M_AmbientMaterial;
//uniform vec4 M_DiffuseLightColor;
//uniform vec4 M_DiffuseMaterial;
void main()
{
// Ambient
vec4 M_AmbientLightColor = vec4(0.2, 0.2, 0.2, 1.0);
vec4 M_AmbientMaterial = vec4(0.2, 0.2, 0.2, 1.0);
vec4 ambientColor = M_AmbientLightColor * M_AmbientMaterial;
// Diffuse
vec3 M_LightPos = vec3(10.0, 10.0, 0.0);
vec3 LightNormal = normalize(M_LightPos); // 指向光源的单位向量
vec3 NormalNormal = normalize(M_normal); // 法线的单位向量
// 点乘获取光照强度
vec4 M_DiffuseLightColor = vec4(1.0, 1.0, 1.0, 1.0);
vec4 M_DiffuseMaterial = vec4(0.9, 0.9, 0.9, 1.0);
vec4 diffuseColor = M_DiffuseLightColor * M_DiffuseMaterial *
max(0.0, dot(NormalNormal, LightNormal));
// 镜面反射
vec4 specularLightColor = vec4(1.0, 1.0, 1.0, 1.0);
vec4 specularMaterial = vec4(0.4, 0.4, 0.4, 1.0);
vec3 reflerDir = normalize(reflect(-LightNormal, NormalNormal));
vec3 eyeDir = normalize(vec3(0.0) - M_WordPos);
vec4 specularColor = specularLightColor * specularMaterial *
pow(max(0.0, dot(reflerDir, eyeDir)), 180);
gl_FragColor = ambientColor + texture2D(U_MainTexture, M_coord) * 1
+ specularColor;
}为了使模型看的更清楚，我没用漫反射。如果使用漫反射可以将最后一句改成：
gl_FragColor = ambientColor +
texture2D(U_MainTexture, M_coord) * diffuseColor +
specularColor;
分享标题：基于Qt的OpenGL可编程管线学习（2）-obj模型绘制
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