GLSL删除用过的变量

我在代码中有一个非常奇怪的问题，添加了名为" coord"的VEC2，因为它包含了我的纹理坐标，这些都应该传递到我的Vertex Shader中，并通过几何着色器，在最终传递到碎片着色器之前，将其用于纹理映射。但是由于某种原因，GLSL编译器正在优化VEC2输入，使用glVertexAttribPointer将其分配给NETS NOT结果，并使用glGetUniformLocation(gShaderProgram, "coord");返回-1仔细检查其位置-1，这表明GLSL编译器已通过GLSL编译器进行了优化，为什么？据我所知，编译器只会优化不促成着色器输出的值，而是在每个着色器阶段中用作输出。这是一个Uni任务，所以这对我来说都是全新的。

顶点着色器

#version 440
layout(location = 0) in vec3 vertex_position;
layout(location = 1) in vec3 vertex_color;
layout(location = 2) in vec2 coord;
layout(location = 20) uniform vec4 test;
layout(binding = 3, std140) uniform uniformBlock
{
    float v1;
    float v2;
    float v3;
    float v4;
};
uniform mat4 m;
uniform mat4 p;
uniform mat4 v;
out vData
{
    mat4 m;
    mat4 p;
    mat4 v;
    vec4 test;
    vec4 color;
    vec2 tex_coord;
}vertices;
void main() {
    vertices.m = m;
    vertices.p = p;
    vertices.v = v;
    vertices.test = test;
    vertices.tex_coord = coord;
    vertices.color = vec4(vertex_color, 1.0);
    gl_Position = vec4(vertex_position, 1.0);
}

几何着色器

#version 400
layout (triangles) in;
layout (triangle_strip, max_vertices = 6) out;
in vData
{
    mat4 m;
    mat4 p;
    mat4 v;
    vec4 test;
    vec4 color;
    vec2 tex_coord;
} vertices[];
out fData
{
    vec3 normal;
    vec4 color;
    mat4 v;
    vec2 tex_coord;
} frag;
void main()
{
    vec3 A = gl_in[2].gl_Position.xyz - gl_in[0].gl_Position.xyz;
    vec3 B = gl_in[1].gl_Position.xyz - gl_in[0].gl_Position.xyz;
    vec3 normal = normalize(cross(A,B));
    int i;
    for(i = 0;i < gl_in.length();i++)
    {
        gl_Position = (vertices[i].p * vertices[i].v * vertices[i].m) * gl_in[i].gl_Position;
        frag.normal = normalize(vec3(vertices[i].m * vec4(normal,0)));
        frag.color = vertices[i].color;
        frag.v = vertices[i].v;
        frag.tex_coord = vertices[i].tex_coord;
        EmitVertex();
    }
    EndPrimitive();
    for(i = 0;i < gl_in.length();i++)
    {
        gl_Position = vertices[i].p * vertices[i].v * vertices[i].m * (gl_in[i].gl_Position + vec4(normal,0));
        frag.normal = normalize(vec3(vertices[i].m * vec4(normal,0)));
        frag.color = vertices[i].color;
        frag.v = vertices[i].v;
        frag.tex_coord = vertices[i].tex_coord;
        EmitVertex();
    }
    EndPrimitive();
}

碎片着色器

#version 400
out vec4 fragment_color;
const float PI = 3.14159265;
uniform sampler2D texture0;
in fData
{
    vec3 normal;
    vec4 color;
    mat4 v;
    vec2 tex_coord;
} frag;

void main () {
    vec3 n = normalize(frag.normal);
    float intensity = min(max(dot(n, vec3(0,0,-1)), 0.0), 1.0);
    //fragment_color = frag.color * intensity * frag.tex_coord.s;
    fragment_color = texture2D(texture0, frag.tex_coord.st);
}

main.cpp

#include <vector>
#include <windows.h>
#include <iostream>
#include <string>
#include <fstream>
#include <streambuf>
#include <chrono>
#include <gl/glew.h>
#include <gl/GL.h>
# define M_PI           3.14159265358979323846
#include "glmglm.hpp"
#include "glmgtcmatrix_transform.hpp"
#include "bth_image.h"
#pragma comment(lib, "opengl32.lib")
#pragma comment(lib, "glew32.lib")
using namespace std;
using namespace glm;
HWND InitWindow(HINSTANCE hInstance);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
HGLRC CreateOpenGLContext(HWND wndHandle);
GLuint gVertexBuffer = 0;
GLuint gVertexAttribute = 0;
GLuint gShaderProgram = 0;
GLuint textures[1];
mat4x4 view;
mat4x4 world;
mat4x4 projection;
float DT;
struct CPUvalues
{
    float v1;
    float v2;
    float v3;
    float v4;
};
CPUvalues Gv = { 0.5, 0, 0, 0 };
GLuint gu = 0;
#define BUFFER_OFFSET(i) ((char *)nullptr + (i))
void CreateShaders()
{
    GLuint vs = glCreateShader(GL_VERTEX_SHADER);
    ifstream shaderFile("VertexShader.glsl");
    std::string shaderText((std::istreambuf_iterator<char>(shaderFile)), std::istreambuf_iterator<char>());
    shaderFile.close();
    const char* shaderTextPtr = shaderText.c_str();
    glShaderSource(vs, 1, &shaderTextPtr, nullptr);
    glCompileShader(vs);
    //create fragment shader | same process.
    GLuint fs = glCreateShader(GL_FRAGMENT_SHADER);
    shaderFile.open("Fragment.glsl");
    shaderText.assign((std::istreambuf_iterator<char>(shaderFile)), std::istreambuf_iterator<char>());
    shaderFile.close();
    shaderTextPtr = shaderText.c_str();
    glShaderSource(fs, 1, &shaderTextPtr, nullptr);
    glCompileShader(fs);
    GLuint gs = glCreateShader(GL_GEOMETRY_SHADER);
    shaderFile.open("GMshader.glsl");
    shaderText.assign((std::istreambuf_iterator<char>(shaderFile)), std::istreambuf_iterator<char>());
    shaderFile.close();
    shaderTextPtr = shaderText.c_str();
    glShaderSource(gs, 1, &shaderTextPtr, nullptr);
    glCompileShader(gs);

    GLint success = 0;
    glGetShaderiv(gs, GL_COMPILE_STATUS, &success);
    if (success == GL_FALSE)
    {
        GLint logSize = 0;
        glGetShaderiv(gs, GL_INFO_LOG_LENGTH, &logSize);
        std::vector<GLchar> errorLog(logSize);
        glGetShaderInfoLog(gs, logSize, &logSize, &errorLog[0]);
        for (int i = 0; i < errorLog.size(); i++)
        {
            cout << errorLog.at(i);
        }
    }
    //link shader program (connect vs and ps)
    gShaderProgram = glCreateProgram();
    glAttachShader(gShaderProgram, fs);
    glAttachShader(gShaderProgram, gs);
    glAttachShader(gShaderProgram, vs);
    glBindAttribLocation(gShaderProgram, 1, "vertices");
    glEnable(GL_TEXTURE_2D);
    glGenTextures(1, textures);
    glBindTexture(GL_TEXTURE_2D, textures[0]);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, BTH_IMAGE_WIDTH, BTH_IMAGE_HEIGHT, 0, GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid*)BTH_IMAGE_DATA);

    glLinkProgram(gShaderProgram);

    GLint isLinked = 0;
    glGetProgramiv(gShaderProgram, GL_LINK_STATUS, &isLinked);
    if (isLinked == GL_FALSE)
    {
        GLint maxLength = 0;
        glGetProgramiv(gShaderProgram, GL_INFO_LOG_LENGTH, &maxLength);
        std::vector<GLchar> infoLog(maxLength);
        glGetProgramInfoLog(gShaderProgram, maxLength, &maxLength, &infoLog[0]);
        for (GLint i = 0; i < maxLength; i++)
        {
            cout << infoLog.at(i);
        }
    }
}
void CreateTriangleData()
{
    // this is how we will structure the input data for the vertex shader
    // every six floats, is one vertex.
    struct TriangleVertex
    {
        float x, y, z;
        float r, g, b;
        float s, t;
    };
    // create the actual data in plane Z = 0
    TriangleVertex triangleVertices[6] = 
    {
        // pos and color for each vertex
        { -0.5f, 0.5f, 0.0f,    1.0f, 0.0f, 0.0f,   1.0f, 0.0f },
        { 0.5f, -0.5f, 0.0f,    0.0f, 1.0f, 0.0f,   1.0f, 0.0f },
        { -0.5f, -0.5f, 0.0f,   0.0f, 0.0f, 1.0f,   1.0f, 0.0f },
        { 0.5f, 0.5f, 0.0f,     0.0f, 0.0f, 1.0f,   1.0f, 0.0f },
        { 0.5f, -0.5f, 0.0f,    0.0f, 1.0f, 0.0f,   1.0f, 0.0f },
        { -0.5f, 0.5f, 0.0f,    1.0f, 0.0f, 0.0f,   1.0f, 0.0f }

    };
    // Vertex Array Object (VAO) 
    glGenVertexArrays(1, &gVertexAttribute);
    // bind == enable
    glBindVertexArray(gVertexAttribute);
    // this activates the first and second attributes of this VAO
    glEnableVertexAttribArray(0); 
    glEnableVertexAttribArray(1);
    // create a vertex buffer object (VBO) id
    glGenBuffers(1, &gVertexBuffer);
    // Bind the buffer ID as an ARRAY_BUFFER
    glBindBuffer(GL_ARRAY_BUFFER, gVertexBuffer);
    // This "could" imply copying to the GPU, depending on what the driver wants to do...
    glBufferData(GL_ARRAY_BUFFER, sizeof(triangleVertices), triangleVertices, GL_STATIC_DRAW);
    // query where which slot corresponds to the input vertex_position in the Vertex Shader 
    GLint vertexPos = glGetAttribLocation(gShaderProgram, "vertex_position");
    // specify that: the vertex attribute "vertexPos", of 3 elements of type FLOAT, not normalized, with STRIDE != 0,
    //               starts at offset 0 of the gVertexBuffer (it is implicitly bound!)
    glVertexAttribPointer(vertexPos, 3,    GL_FLOAT, GL_FALSE,     sizeof(TriangleVertex), BUFFER_OFFSET(0));
    // query where which slot corresponds to the input vertex_color in the Vertex Shader 
    GLint vertexColor = glGetAttribLocation(gShaderProgram, "vertex_color");
    cout << "vertex pos " << vertexPos << endl;
    cout << "vertex color " << vertexColor << endl;
    // specify that: the vertex attribute "vertex_color", of 3 elements of type FLOAT, not normalized, with STRIDE != 0,
    //               starts at offset (12 bytes) of the gVertexBuffer 
    glVertexAttribPointer(vertexColor, 3,    GL_FLOAT, GL_FALSE,     sizeof(TriangleVertex), BUFFER_OFFSET(sizeof(float)*3));
    cout << glGetError() << endl;

    GLint tex_coord = glGetUniformLocation(gShaderProgram, "coord");
    cout << "coord " << tex_coord << endl;
    glVertexAttribPointer(tex_coord, 2, GL_FLOAT, GL_FALSE, sizeof(TriangleVertex), BUFFER_OFFSET(sizeof(float) * 6));
    cout << glGetError() << endl;
}
void SetViewport()
{
    glViewport(0, 0, 640, 480);
}
void Render()
{
    // set the color TO BE used
    glClearColor(0, 0, 0, 1);
    // use the color to clear the color buffer
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glUseProgram(gShaderProgram);
    glBindVertexArray(gVertexAttribute);
    glGenBuffers(1, &gu);
    glBindBuffer(GL_UNIFORM_BUFFER, gu);

    glBufferSubData(GL_UNIFORM_BUFFER, 0, sizeof(CPUvalues), &Gv);
    GLint OG_loc = glGetUniformLocation(gShaderProgram, "test");
    GLint _p = glGetUniformLocation(gShaderProgram, "p");
    GLint _m = glGetUniformLocation(gShaderProgram, "m");
    GLint _v = glGetUniformLocation(gShaderProgram, "v");

    GLuint unit = 0;
    GLint texture0 = glGetUniformLocation(gShaderProgram, "texture0");
    //cout << glGetUniformLocation(gShaderProgram, "coord") << endl;;
    glActiveTexture(GL_TEXTURE0 + unit);
    glBindTexture(GL_TEXTURE_2D, textures[0]);
    glUniform1i(texture0, unit);
    glUniformMatrix4fv(_p, 1, GL_FALSE, &projection[0][0]);
    glUniformMatrix4fv(_m, 1, GL_FALSE, &world[0][0]);
    glUniformMatrix4fv(_v, 1, GL_FALSE, &view[0][0]);
    glUniform4f(OG_loc, Gv.v1, Gv.v2, Gv.v3, Gv.v4);
    // draw 3 vertices starting from index 0 in the vertex array currently bound (VAO), with current in-use shader
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_CULL_FACE);
    glFrontFace(GL_CW);
    glCullFace(GL_BACK);
    glDrawArrays(GL_TRIANGLES, 0, 6);
}
int WINAPI wWinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int nCmdShow )
{
    AllocConsole();
    freopen("CONOUT$", "w", stdout);
    DT = 0.016;
    MSG msg = { 0 };
    HWND wndHandle = InitWindow(hInstance); //1. Skapa fönster
    if (wndHandle)
    {
        HDC hDC = GetDC(wndHandle);
        HGLRC hRC = CreateOpenGLContext(wndHandle); //2. Skapa och koppla OpenGL context
        glewInit(); //3. Initiera The OpenGL Extension Wrangler Library (GLEW)
        SetViewport(); //4. Sätt viewport
        CreateShaders(); //5. Skapa vertex- och fragment-shaders
        CreateTriangleData(); //6. Definiera triangelvertiser, 7. Skapa vertex buffer object (VBO), 8.Skapa vertex array object (VAO)
        ShowWindow(wndHandle, nCmdShow);
        view = lookAt(vec3(0, 0, -2), vec3(0, 0, 0), vec3(0, 1, 0));
        mat4x4 sm;
        sm = scale(sm, vec3(1, 1, 1));
        mat4x4 tm;
        tm = translate(tm, vec3(0, 0, 0));
        mat4x4 rm;
        rm = mat4x4(1);
        projection = perspective<float>(M_PI*0.45, 640 / 480, 0.1, 20);

        while (WM_QUIT != msg.message)
        {
            auto start_time = chrono::high_resolution_clock::now();
            //Gv.v1 += 0.05 * DT;
            Gv.v1 += 1 * DT;
            world = tm * rotate(rm, Gv.v1, vec3(0, 1, 0)) * sm;

            if (PeekMessage(&msg, nullptr, 0, 0, PM_REMOVE))
            {
                TranslateMessage(&msg);
                DispatchMessage(&msg);
            }
            else
            {
                Render(); //9. Rendera
                SwapBuffers(hDC); //10. Växla front- och back-buffer
            }
            auto final_time = chrono::high_resolution_clock::now() - start_time;
            DT = chrono::duration_cast<std::chrono::milliseconds>(final_time).count() / (double)1000;
        }
        wglMakeCurrent(NULL, NULL);
        ReleaseDC(wndHandle, hDC);
        wglDeleteContext(hRC);
        DestroyWindow(wndHandle);
    }
    return (int) msg.wParam;
}
HWND InitWindow(HINSTANCE hInstance)
{
    WNDCLASSEX wcex = { 0 };
    wcex.cbSize = sizeof(WNDCLASSEX); 
    wcex.style          = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = WndProc;
    wcex.hInstance      = hInstance;
    wcex.lpszClassName = L"BTH_GL_DEMO";
    if( !RegisterClassEx(&wcex) )
        return false;
    RECT rc = { 0, 0, 640, 480 };
    AdjustWindowRect( &rc, WS_OVERLAPPEDWINDOW, FALSE );
    HWND handle = CreateWindow(
        L"BTH_GL_DEMO",
        L"BTH OpenGL Demo",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        rc.right - rc.left,
        rc.bottom - rc.top,
        nullptr,
        nullptr,
        hInstance,
        nullptr);
    return handle;
}
LRESULT CALLBACK WndProc( HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam )
{
    switch (message) 
    {
    case WM_DESTROY:
        PostQuitMessage(0);
        break;      
    }
    return DefWindowProc(hWnd, message, wParam, lParam);
}
HGLRC CreateOpenGLContext(HWND wndHandle)
{
    //get handle to a device context (DC) for the client area
    //of a specified window or for the entire screen
    HDC hDC = GetDC(wndHandle);
    //details: http://msdn.microsoft.com/en-us/library/windows/desktop/dd318286(v=vs.85).aspx
    static  PIXELFORMATDESCRIPTOR pixelFormatDesc =
    {
        sizeof(PIXELFORMATDESCRIPTOR),    // size of this pfd  
        1,                                // version number  
        PFD_DRAW_TO_WINDOW |              // support window  
        PFD_SUPPORT_OPENGL |              // support OpenGL  
        PFD_DOUBLEBUFFER,                 // double buffered        
        PFD_TYPE_RGBA,                    // RGBA type  
        32,                               // 32-bit color depth  
        0, 0, 0, 0, 0, 0,                 // color bits ignored  
        0,                                // no alpha buffer  
        0,                                // shift bit ignored  
        0,                                // no accumulation buffer  
        0, 0, 0, 0,                       // accum bits ignored  
        0,                                // 0-bits for depth buffer <-- modified by Stefan      
        0,                                // no stencil buffer  
        0,                                // no auxiliary buffer  
        PFD_MAIN_PLANE,                   // main layer  
        0,                                // reserved  
        0, 0, 0                           // layer masks ignored  
    };
    //attempt to match an appropriate pixel format supported by a
    //device context to a given pixel format specification.
    int pixelFormat = ChoosePixelFormat(hDC, &pixelFormatDesc);
    //set the pixel format of the specified device context
    //to the format specified by the iPixelFormat index.
    SetPixelFormat(hDC, pixelFormat, &pixelFormatDesc);
    //create a new OpenGL rendering context, which is suitable for drawing
    //on the device referenced by hdc. The rendering context has the same
    //pixel format as the device context.
    HGLRC hRC = wglCreateContext(hDC);
    //makes a specified OpenGL rendering context the calling thread's current
    //rendering context. All subsequent OpenGL calls made by the thread are
    //drawn on the device identified by hdc. 
    wglMakeCurrent(hDC, hRC);
    return hRC;
}