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我正试图围绕 OpenGL 中各种类型的 GLSL 着色器。目前，我正在为 2d 分层瓷砖实现而苦苦挣扎。由于某种原因，传入我的着色器的 int 值始终为 0（或更可能为 null）。

我目前有一个由 20x20 瓷砖组成的 2048x2048px 2d 纹理。我正在尝试用它来纹理一个四边形，并根据我传递给顶点着色器的整数块来更改图块的索引。

我正在传递一个 vec2 的浮点数作为四边形的位置（实际上是一个 TRIANGLE_STRIP）。我还尝试传入 6 个整数，代表 6 层瓷砖。

我的输入：

// Build and compile our shader program
Shader ourShader("b_vertex.vertexShader", "b_fragment.fragmentShader");

const int floatsPerPosition = 2;
const int intsPerTriangle = 6;
const int numVertices = 4;
const int sizeOfPositions = sizeof(float) * numVertices * floatsPerPosition;
const int sizeOfColors = sizeof(int) * numVertices * intsPerTriangle;
const int numIndices = 4;
const int sizeOfIndices = sizeof(int) * numIndices;

float positions[numVertices][floatsPerPosition] =
{
    { -1, 1 },
    { -1, -1 },
    { 1, 1 },
    { 1, -1 },
};

// ints indicating Tile Index
int colors[numVertices][intsPerTriangle] =
{
    { 1, 2, 3, 4, 5, 6 },
    { 1, 2, 3, 4, 5, 6 },
    { 1, 2, 3, 4, 5, 6 },
    { 1, 2, 3, 4, 5, 6 },
};

// Indexes on CPU
int indices[numVertices] =
{
    0, 1, 2, 3,
};

我的设置：

GLuint vao, vbo1, vbo2, ebo; // Identifiers of OpenGL objects

glGenVertexArrays(1, &vao); // Create new VAO
                            // Binded VAO will store connections between VBOs and attributes
glBindVertexArray(vao);

glGenBuffers(1, &vbo1); // Create new VBO
glBindBuffer(GL_ARRAY_BUFFER, vbo1); // Bind vbo1 as current vertex buffer
                                     // initialize vertex buffer, allocate memory, fill it with data
glBufferData(GL_ARRAY_BUFFER, sizeOfPositions, positions, GL_STATIC_DRAW);
// indicate that current VBO should be used with vertex attribute with index 0
glEnableVertexAttribArray(0);
// indicate how vertex attribute 0 should interpret data in connected VBO
glVertexAttribPointer(0, floatsPerPosition, GL_FLOAT, GL_FALSE, 0, 0);

glGenBuffers(1, &vbo2); // Create new VBO
glBindBuffer(GL_ARRAY_BUFFER, vbo2); // Bind vbo2 as current vertex buffer
                                     // initialize vertex buffer, allocate memory, fill it with data
glBufferData(GL_ARRAY_BUFFER, sizeOfColors, colors, GL_STATIC_DRAW);
// indicate that current VBO should be used with vertex attribute with index 1
glEnableVertexAttribArray(1);
// indicate how vertex attribute 1 should interpret data in connected VBO
glVertexAttribPointer(1, intsPerTriangle, GL_INT, GL_FALSE, 0, 0);

// Create new buffer that will be used to store indices
glGenBuffers(1, &ebo);
// Bind index buffer to corresponding target
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
// ititialize index buffer, allocate memory, fill it with data
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeOfIndices, indices, GL_STATIC_DRAW);

// reset bindings for VAO, VBO and EBO
glBindVertexArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);



// Load and create a texture 
GLuint texture1 = loadBMP_custom("uvtemplate3.bmp");

GLuint texture2 = loadBMP_custom("texture1.bmp");

我的画法：

// Game loop
while (!glfwWindowShouldClose(window))
{
    // Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functions
    glfwPollEvents();

    // Render
    // Clear the colorbuffer
    glClearColor(1.f, 0.0f, 1.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // Activate shader
    ourShader.Use();

    // Bind Textures using texture units
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texture1);

    //add some cool params
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
    float borderColor[] = { 0.45f, 0.25f, 0.25f, 0.25f };
    glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, borderColor);

    glUniform1i(glGetUniformLocation(ourShader.Program, "ourTexture1"), 0);
    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, texture2);
    glUniform1i(glGetUniformLocation(ourShader.Program, "ourTexture2"), 1);

    // Draw container
    //glBindVertexArray(VAO);
    //glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
    glBindVertexArray(vao);
    //glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
    glDrawElements(GL_TRIANGLE_STRIP, numIndices, GL_UNSIGNED_INT, NULL);

    glBindVertexArray(0);

    // Swap the screen buffers
    glfwSwapBuffers(window);
}

我的着色器绝对有效，因为我可以通过对 vertexShader 中的值进行硬编码来调整输出。我的怀疑是我没有正确/以正确的格式传递值，或者没有在某个地方指出每个顶点需要包含 int[6]。

我无法从 int Base[6] 中的布局（位置 = 1）中读取任何内容；我已经尝试了几乎所有我能想到的。分别声明每个 int，尝试读取两个 ivec3、uint 以及我能想到的任何其他内容，但一切都返回 0。

以下是我的顶点和片段着色器的完整性：

#version 330 core
layout (location = 0) in vec2 position;
layout (location = 1) in int Base[6];

out vec2 TexCoord;
out vec2 TexCoord2;
out vec2 TexCoord3;
out vec2 TexCoord4;
out vec2 TexCoord5;
out vec2 TexCoord6;

//  0.5f,  0.5f,// 0.0f,   118.0f, 0.0f, 0.0f,   0.0f, 0.0f, // Top Right
//  0.5f, -0.5f,// 0.0f,   118.0f, 1.0f, 0.0f,   0.0f,0.009765625f, // Bottom Right
//  -0.5f, -0.5f,// 0.0f,   118.0f, 0.0f, 1.0f,   0.009765625f, 0.009765625f, // Bottom Left
//  -0.5f,  0.5f//, 0.0f,   118.0f, 1.0f, 0.0f,   0.009765625f, 0.0f  // Top Left 

void main()
{

int curBase = Base[5];

int curVertex = gl_VertexID % 4;
vec2 texCoord = (curVertex == 0?
vec2(0.0,0.0):(
curVertex == 1?
vec2(0.0,0.009765625):(
curVertex == 2?
vec2(0.009765625,0.0):(
curVertex == 3?
vec2(0.009765625,0.009765625):(
vec2(0.0,0.0)))))
);
gl_Position = vec4(position, 0.0f, 1.0f);

TexCoord = vec2(texCoord.x + ((int(curBase)%102)*0.009765625f)
, (1.0 - texCoord.y) - ((int(curBase)/102)*0.009765625f));
//curBase = Base+1;
TexCoord2 = vec2(texCoord.x + ((int(curBase)%102)*0.009765625f)
, (1.0 - texCoord.y) - ((int(curBase)/102)*0.009765625f));
//curBase = Base+2;
TexCoord3 = vec2(texCoord.x + ((int(curBase)%102)*0.009765625f)
, (1.0 - texCoord.y) - ((int(curBase)/102)*0.009765625f));
}

分段：

#version 330 core
//in vec3 ourColor;
in vec2 TexCoord;
in vec2 TexCoord2;
in vec2 TexCoord3;
in vec2 TexCoord4;
in vec2 TexCoord5;
in vec2 TexCoord6;

out vec4 color;

// Texture samplers
uniform sampler2D ourTexture1;
uniform sampler2D ourTexture2;

void main()
{
color = (texture(ourTexture2, TexCoord )== vec4(1.0,0.0,1.0,1.0)?
(texture(ourTexture2, TexCoord2 )== vec4(1.0,0.0,1.0,1.0)?
(texture(ourTexture2, TexCoord3 )== vec4(1.0,0.0,1.0,1.0)?
(texture(ourTexture2, TexCoord4 )== vec4(1.0,0.0,1.0,1.0)?
(texture(ourTexture2, TexCoord5 )== vec4(1.0,0.0,1.0,1.0)?
(texture(ourTexture2, TexCoord6 )== vec4(1.0,0.0,1.0,1.0)?
    vec4(0.0f,0.0f,0.0f,0.0f)
:texture(ourTexture2, TexCoord6 ))
:texture(ourTexture2, TexCoord5 ))
:texture(ourTexture2, TexCoord4 ))
:texture(ourTexture2, TexCoord3 ))
:texture(ourTexture2, TexCoord2 ))
:texture(ourTexture2, TexCoord ));
}
4

1 回答 1

3

这在两种不同的方面是错误的：

glVertexAttribPointer(1, intsPerTriangle, GL_INT, GL_FALSE, 0, 0);

GL 中的顶点属性可以是 2 到 4 个分量的标量或向量。因此，size参数 ofglVertexAttribPointer可以取值 1、2、3 或 4。使用不同的值 ( intsPerTriangle == 6) 意味着调用只会产生GL_INVALID_VALUE错误并且没有任何效果，因此您甚至不需要设置指针。

如果您想为每个顶点传递 6 个值，您可以使用 6 个不同的标量属性（消耗 6 个属性槽），或者将其打包到一些向量中，例如 2 个 3d 向量（仅消耗 2 个槽）。无论您选择什么包装，您都需要为使用中的每个属性槽设置适当的属性指针。

However, glVertexAttribPointer is also the wrong function for your use case. It is defining floating-point attributes, which musthave matching declarations as float/vec* in the shader. The fact that you can input GL_INT just means that the GPU can do the conversion to floating-point on the fly for you.

If you want to use an int or ivec (or their unsigned counterparts) attribute, you have to use glVertexAttribIPointer (note the I in that function name) when setting up the attribute.

于 2016-07-04T20:29:26.673 回答