gluPerspective在OpenGL 3.1中删除了,任何替换？

Question

我正在尝试在网上阅读一些OpenGL教程.问题是我找到了一些旧的gluPerspective().gluPerspective在OpenGL 3.0中已弃用,在3.1中已删除.

我可以用什么功能代替？

我正在使用安装了最新FreeGlut的C++.

Answer 1

您必须手动计算矩阵,然后将其传递给OpenGL.

计算矩阵

这段代码基于gluPerspective文档.

 void BuildPerspProjMat(float *m, float fov, float aspect,
 float znear, float zfar)
 {
  float f = 1/tan(fov * PI_OVER_360);

  m[0]  = f/aspect;
  m[1]  = 0;
  m[2]  = 0;
  m[3]  = 0;

  m[4]  = 0;
  m[5]  = f;
  m[6]  = 0;
  m[7]  = 0;

  m[8]  = 0;
  m[9]  = 0;
  m[10] = (zfar + znear) / (znear - zfar);
  m[11] = -1;

  m[12] = 0;
  m[13] = 0;
  m[14] = 2*zfar*znear / (znear - zfar);
  m[15] = 0;
 }

有一个名为OpenGL Mathematics的C++库可能很有用.

在OpenGL 3.1中加载Matrix

我还是OpenGL 3.1 API的新手,但你需要更新GPU上的矩阵,然后在你的顶点着色器中使用它来获得正确的视角.以下代码只使用glUniform4fv将矩阵加载到视频卡上.

{
  glUseProgram(shaderId);
  glUniformMatrix4fv(glGetUniformLocation(shaderId, "u_proj_matrix"),
                     1, GL_FALSE, theProjectionMatrix);
  RenderObject();
  glUseProgram(0);
}

来自随机博客的简单顶点着色器(通过堆栈溢出找到).

attribute vec4      a_position;
attribute vec4      a_color;

varying vec4        v_color;

uniform mat4 u_proj_matrix;
uniform mat4 u_model_matrix;

void main() {
  mat4 mvp_matrix = u_proj_matrix * u_model_matrix;
  v_color = a_color;
  gl_Position = mvp_matrix * a_position;
}

Answer 2

使用GLM.

glm::mat4 projection = glm::perspective(
  // FOV & aspect
  60.0f, 16.0f / 10.0f, 
  // Near and far planes
  0.001f, 1000f);

// If you're using the now deprecated matrix stacks
glMatrixMode(GL_PROJECTION);
glLoadMatrixf(glm::value_ptr(projection));

// if you're using the new shader based pipelines
GLint projectionUniformLocation = ...;
glUniformMatrix4fv(projectionUniformLocation, 1, GL_FALSE, 
  glm::value_ptr(projection));

注意,如果你已经GLM_FORCE_RADIANS定义了那么你应该在透视函数中使用弧度,而不是度...

glm::mat4 projection = glm::perspective(
  // FOV & aspect
  PI / 3.0f, 16.0f / 10.0f, 
  // Near and far planes
  0.001f, 1000f);

Answer 3

从我的一个旧项目中复制:

// The following code is a fancy bit of math that is eqivilant to calling:
// gluPerspective( fieldOfView/2.0f, width/height , 0.1f, 255.0f )
// We do it this way simply to avoid requiring glu.h
GLfloat zNear = 0.1f;
GLfloat zFar = 255.0f;
GLfloat aspect = float(width)/float(height);
GLfloat fH = tan( float(fieldOfView / 360.0f * 3.14159f) ) * zNear;
GLfloat fW = fH * aspect;
glFrustum( -fW, fW, -fH, fH, zNear, zFar );