Question

此代码必须绘制两条正弦线。这里有两条常用线路通过着色器转换为正弦线。我有一个任务是旋转其中一个（例如，45度或90度），怎么做？

void CMyApplication::OnDraw()
{

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glUseProgramObjectARB(m_program);

    glUniform1fARB(m_amplitudeUniformLocation, 0.3f);
    glUniform1fARB(m_phaseUniformLocation, m_phase);
    glUniform1fARB(m_frequencyUniformLocation, M_PI);
    glUniform1fARB(m_colourUniformLocation, 0.0f);
    //glUniform1fARB(m_rotateUniformLocation, true);
    //glLoadIdentity();
    //glRotatef(90.0f, 0.0f, 0.0f, 0.0f);
    glBegin(GL_LINE_STRIP);
    {
        for (float x = -1; x <= 1.05; x += 0.01)
        {
            glVertex3f(x, 0, 0);
            glColor3f(0, 0.5, -0.8);
        }
    }
    glEnd();
    //glLoadIdentity();
    //glRotatef(-90.0f, 0.0f, 0.0f, 0.0f);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glUniform1fARB(m_phaseUniformLocation, m_phase - 0.5);
    glUniform1fARB(m_colourUniformLocation, 0.5f);
    //glUniform1fARB(m_rotateUniformLocation, false);

    glBegin(GL_LINE_STRIP);
    {
        for (float x = -1; x <= 1.05; x += 0.01)
        {
            glVertex3f(x, -0.5, 0);
            glColor3f(0, -0.5, 0.8);
        }
    }
    glEnd();

    __glewMatrixRotatefEXT(GL_MODELVIEW, 45, 0, 0, 1); //THIS STRING HAS BEEN RESOLVED         //MY PROBLEM

    glUseProgramObjectARB(NULL);

    glutSwapBuffers();
}

下面的着色器：

uniform float phase;                
uniform float amplitude;            
uniform float frequency;                           
void main()                     
{                                   
    vec4 v = gl_Vertex;                                 
    v.y += amplitude * sin(frequency * v.x + phase);    
    gl_Position = gl_ModelViewProjectionMatrix * v;     
    gl_FrontColor = gl_Color;       
 }

Answer 1

因为您正在使用着色器，所以glRotatef将无法按预期运行。使用着色器启用可编程管道后，将关闭固定功能管道转换调用。所以从本质上讲，除非你已经在顶点着色器中使用了正确的矩阵，否则glRotatef在此处不执行任何操作。

要获得您想要的结果，您需要生成适当的旋转矩阵，将其传递到均匀变量中的顶点着色器，然后在应用WVP变换之前将其乘以创建的线。最终结果应该为您提供旋转线。

如何旋转图像基元？我曾尝试使用glRotatef函数，但它没有得到结果

1 个答案: