我正在使用一些教程(http://opengl-tutorial.org)学习OpenGL 3.3。在我正在使用的教程中,有一个顶点着色器可以执行以下操作:

教程着色器源

#version 330 core

// Input vertex data, different for all executions of this shader.
layout(location = 0) in vec3 vertexPosition_modelspace;

// Values that stay constant for the whole mesh.
uniform mat4 MVP;

void main(){

    // Output position of the vertex, in clip space : MVP * position
    gl_Position =  MVP * vec4(vertexPosition_modelspace,1);

}

但是,当我尝试在应用程序中模拟相同的行为时,会得到以下信息:
error: implicit cast from "vec4" to "vec3"

看到这一点之后,我不确定是否是因为我使用的是4.2版本的着色器而不是3.3的着色器,所以更改了所有内容以匹配作者使用的内容,之后仍然收到相同的错误。

因此,我更改了着色器以执行此操作:

我的(最新)来源
#version 330 core

layout(location = 0) in vec3 vertexPosition_modelspace;

uniform mat4 MVP;

void main()
{
    vec4 a = vec4(vertexPosition_modelspace, 1);

    gl_Position.xyz = MVP * a;
}

当然,这仍然会产生相同的错误。

有谁知道为什么会这样,还有什么解决方案?我不确定这是否是我的调用代码(以防万一,我已经发布了该代码)。

call 代码
static const GLfloat T_VERTEX_BUF_DATA[] =
{
    // x, y z
    -1.0f, -1.0f, 0.0f,
     1.0f, -1.0f, 0.0f,
     0.0f, 1.0f, 0.0f
};

static const GLushort T_ELEMENT_BUF_DATA[] =
{ 0, 1, 2 };

void TriangleDemo::Run(void)
{
    glClear(GL_COLOR_BUFFER_BIT);

    GLuint matrixID = glGetUniformLocation(mProgramID, "MVP");

    glUseProgram(mProgramID);

    glUniformMatrix4fv(matrixID, 1, GL_FALSE, &mMVP[0][0]); // This sends our transformation to the MVP uniform matrix, in the currently bound vertex shader

    const GLuint vertexShaderID = 0;

    glEnableVertexAttribArray(vertexShaderID);
    glBindBuffer(GL_ARRAY_BUFFER, mVertexBuffer);
    glVertexAttribPointer(
        vertexShaderID, // Specify the ID of the shader to point to (in this case, the shader is built in to GL, which will just produce a white triangle)
        3,              // Specify the number of indices per vertex in the vertex buffer
        GL_FLOAT,       // Type of value the vertex buffer is holding as data
        GL_FALSE,       // Normalized?
        0,              // Amount of stride
        (void*)0 );     // Offset within the array buffer

    glDrawArrays(GL_TRIANGLES, 0, 3); //0 => start index of the buffer, 3 => number of vertices

    glDisableVertexAttribArray(vertexShaderID);
}

void TriangleDemo::Initialize(void)
{
    glGenVertexArrays(1, &mVertexArrayID);

    glBindVertexArray(mVertexArrayID);

    glGenBuffers(1, &mVertexBuffer);

    glBindBuffer(GL_ARRAY_BUFFER, mVertexBuffer);

    glBufferData(GL_ARRAY_BUFFER, sizeof(T_VERTEX_BUF_DATA), T_VERTEX_BUF_DATA, GL_STATIC_DRAW );

    mProgramID = LoadShaders("v_Triangle", "f_Triangle");

    glm::mat4 projection = glm::perspective(45.0f, 4.0f / 3.0f, 0.1f, 100.0f); // field of view, aspect ratio (4:3), 0.1 units near, to 100 units far

    glm::mat4 view  = glm::lookAt(
                                glm::vec3(4, 3, 3), // Camera is at (4, 3, 3) in world space
                                glm::vec3(0, 0, 0), // and looks at the origin
                                glm::vec3(0, 1, 0)  // this is the up vector - the head of the camera is facing upwards. We'd use (0, -1, 0) to look upside down
                            );

    glm::mat4 model = glm::mat4(1.0f); // set model matrix to identity matrix, meaning the model will be at the origin

    mMVP            = projection * view * model;

}

注释
  • 我在Visual Studio 2012中
  • 我将Shader Maker用于GLSL编辑
  • 最佳答案

    我不能说教程代码有什么问题。

    不过,在“我的最新消息”中

    gl_Position.xyz = MVP * a;
    

    看起来很奇怪,因为您正在将vec4分配给vec3

    编辑

    我无法重现您的问题。

    我使用了一个简单的片段着色器进行测试...
    #version 330 core
    
    void main()
    {
    }
    

    测试“教程着色器源” :
    3.3.11762 Core Profile Context
    Log: Vertex shader was successfully compiled to run on hardware.
    
    Log: Fragment shader was successfully compiled to run on hardware.
    
    Log: Vertex shader(s) linked, fragment shader(s) linked.
    

    测试“我的最新消息” :
    3.3.11762 Core Profile Context
    Log: Vertex shader was successfully compiled to run on hardware.
     WARNING: 0:11: warning(#402) Implicit truncation of vector from size 4 to size 3.
    
    Log: Fragment shader was successfully compiled to run on hardware.
    
    Log: Vertex shader(s) linked, fragment shader(s) linked.
    

    并且在将gl_Position.xyz替换为gl_Position后,警告消失了。

    你的设置是什么?您是否具有正确版本的OpenGL上下文? glGetError()是否保持沉默?

    最后,您的GPU驱动程序是否是最新的?

    09-10 11:57
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