OpenGL渲染四边形

时间:2018-06-27 13:03:33

标签: opengl glsl rendering qtopengl

由于某种原因,我正在渲染的四边形不会显示,而只会渲染黑屏。我已经多次检查了代码,但找不到问题,也许有人可以看到我看不到的内容!

目的是要使四边形跟随摄像机,现在我只想用单色显示四边形,但是我得到的只是一个黑屏。我正在使用QOpenGLWindowQOpenGLFunctions

void CSLFWindow::renderQuad()
{
    float x0 = -(float)1.f, y0 = -(float)1.f;
    float x1 = (float)1.f, y1 = (float)1.f;

    const QVector3D vertices[4] = {
        QVector3D( x0, y0, 0.0f),
        QVector3D( x0, y1, 0.0f),
        QVector3D( x1, y1, 0.0f),
        QVector3D( x1, y0, 0.0f)
    };

    const QVector3D normals[4] = {
        QVector3D(0.0f, 0.0f,1.0f),
        QVector3D(0.0f, 0.0f,1.0f),
        QVector3D(0.0f, 0.0f,1.0f),
        QVector3D(0.0f, 0.0f,1.0f)
    };
    const QVector2D texcoords[4] = {
        QVector2D(0.0f, 1.0f),
        QVector2D(0.0f, 0.0f),
        QVector2D(1.0f, 0.0f),
        QVector2D(1.0f, 1.0f)
    };

      const unsigned int indices[4] = { 3, 2, 1, 0 };

    m_shaderProgram.enableAttributeArray("vVertices");
    m_shaderProgram.enableAttributeArray("vTexCoords");
    m_shaderProgram.enableAttributeArray("vNormals");

    m_shaderProgram.setAttributeArray("vVertices", vertices);
    m_shaderProgram.setAttributeArray("vTexCoords", texcoords);
    m_shaderProgram.setAttributeArray("vNormals", normals);

    glDrawElements(GL_QUADS, 4, GL_UNSIGNED_INT, indices);

    m_shaderProgram.disableAttributeArray("vVertices");
    m_shaderProgram.disableAttributeArray("vTexCoords");
    m_shaderProgram.disableAttributeArray("vNormals");
}

和渲染:

void CSLFWindow::paintGL()
{
      glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

      m_shaderProgram.bind();

      m_model.setToIdentity();
      m_view = m_camera.toMatrix();
      QMatrix4x4 modelMatrix = m_model ;
      QMatrix4x4 modelViewMatrix = m_view * modelMatrix;


      QMatrix4x4 mvp = m_projection * modelViewMatrix;

      m_shaderProgram.setUniformValue("MV", modelViewMatrix);

      m_shaderProgram.setUniformValue("MVP", mvp);           
      m_shaderProgram.setUniformValue("P", m_projection);      

      renderQuad();
      m_shaderProgram.release();
}

我将投影矩阵设置为:

m_view.setToIdentity();
float aspect = h / w;
m_projection.setToIdentity();
m_projection.perspective(
    m_fov,          
    aspect,         
    0.1f,           
    1000.0f);       

这是我的相机参数:

m_cameraPos   = QVector3D(0.0f, 0.0f,  3.0f);
m_cameraFront = QVector3D(0.0f, 0.0f,  -1.0f);
m_cameraUp    = QVector3D(0.0f, 1.0f,  0.0f); 

QMatrix4x4 toMatrix()
{
     QMatrix4x4 vMatrix;
     vMatrix.setToIdentity();
     vMatrix.lookAt(m_cameraPos,  QVector3D(0.0f, 0.0f,  0.0f), 
                    m_cameraUp);

     return vMatrix;
 }

这是我的顶点着色器:

#version 330 core

layout (location = 0)in vec3 vVertices;
layout (location = 1)in vec2 vTexCoords;
layout (location = 2)in vec3 vNormals;

uniform mat4 MV;
uniform mat4 MVP;
uniform mat4 P;

out vec2 FragTexCoord;
out vec3 FragNormals;

void main()
{
   FragTexCoord = vTexCoords;
   FragNormals = vNormals;

   gl_Position = MVP * vec4(vVertices,1);
}

和我的片段着色器:

#version 330 core

out vec4 fragmentColor;

in vec2 FragTexCoord;
in vec3 FragNormals;

void main()
{
    fragmentColor = vec4(1.0,1.0,1.0,1.0);
}

2 个答案:

答案 0 :(得分:0)

嘿,我无法添加评论,但是您可以尝试更改顶点着色器吗?

void main()
{

   FragTexCoord = vTexCoords;
   FragNormals = vNormals;

   gl_Position = vec4(vVertices,1);
}

如果没有看到任何内容,请告诉我,尝试更改索引的顺序

答案 1 :(得分:0)

  

我发现问题出在设置表面格式!当我删除format.setProfile(QSurfaceFormat :: CoreProfile);我看到四边形。但我不明白为什么会发生

GL_QUAD更改为GL_TRIANGLE_FAN,它将起作用:

glDrawElements(GL_TRIANGLE_FAN, 4, GL_UNSIGNED_INT, indices);

GL_QUAD已过时,并已在核心配置文件中删除。

另见Legacy OpenGL - Removed functionalityOpenGL ContextForward compatibility