如何使用计算着色器计算值并将它们存储在 3D 纹理中？
How can I use a compute shader to calculate values and store them in a 3D texture?
我正在尝试使用计算着色器进行三维物理模拟，但无法将任何内容存储到我的 3D 纹理中。我的着色器编译成功，但是当从 3D 纹理中读回任何值时，我得到一个零向量。我之前也没有使用过计算着色器，所以我不确定我是否正确地分配了工作负载以实现我想要的。
我已经在此处的一个小示例中隔离了问题。基本上 compute.glsl 着色器具有统一的 image3D 并使用 imageStore 将 vec4(1,1,0,1) 写入 gl_WorkGroupID。在 C++ 中，我创建了一个 100x100x100 的 3D 纹理并将其绑定到着色器的制服，然后调用 glDispatchCompute(100,100,100) - 据我所知，这将创建 1,000,000 jobs/shader 次调用，纹理中的每个坐标调用一次。在我的 view.glsl 片段着色器中，我读取了一个随机坐标的值（在本例中为 (3,5,7)）并输出它。我用这个阴影一个立方体对象。
我尝试过的所有操作都会导致输出黑色立方体：
这是我的代码（我一直在关注 learnopengl.com，所以除了我扩展了着色器 class 来处理计算着色器之外，它基本上是相同的样板内容）：
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <stb_image.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <learnopengl/shader_m.h>
#include <iostream>
void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow* window);
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
struct vaoinfo
{
unsigned int VBO, VAO, EBO;
vaoinfo() : VAO(0), VBO(0), EBO(0)
{}
};
void create_vao(vaoinfo& info)
{
glGenVertexArrays(1, &info.VAO);
glGenBuffers(1, &info.VBO);
glGenBuffers(1, &info.EBO);
}
void init_vao(vaoinfo& info, float* vertices, int num_vertices, int* indices, int num_indices)
{
glGenVertexArrays(1, &info.VAO);
glGenBuffers(1, &info.VBO);
glGenBuffers(1, &info.EBO);
glBindVertexArray(info.VAO);
glBindBuffer(GL_ARRAY_BUFFER, info.VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(float) * num_vertices, vertices, GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, info.EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(int) * num_indices, indices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
glBindVertexArray(0);
}
int main()
{
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
if (window == NULL)
{
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
vaoinfo cube;
create_vao(cube);
glm::vec3 c(0.5, 0.5, 0.5);
float verts[24] =
{
c.x, -c.y, c.z,
c.x, c.y, c.z,
-c.x, c.y, c.z,
-c.x, -c.y, c.z,
c.x, -c.y, -c.z,
c.x, c.y, -c.z,
-c.x, c.y, -c.z,
-c.x, -c.y, -c.z,
};
int indices[36] =
{
7, 4, 5,
5, 6, 7,
3, 0, 1,
1, 2, 3,
2, 6, 7,
7, 3, 2,
1, 5, 4,
4, 0, 1,
7, 4, 0,
0, 3, 7,
6, 5, 1,
1, 2, 6
};
init_vao(cube, verts, 24, indices, 36);
// Create a 3D texture
unsigned int texId;
glGenTextures(1, &texId);
glBindTexture(GL_TEXTURE_3D, texId);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexImage3D(GL_TEXTURE_3D, 0, GL_RGBA8_SNORM, 100, 100, 100, 0, GL_RGBA, GL_FLOAT, nullptr);
// Create shaders
Shader computeShader("compute.glsl");
Shader viewShader("coords.glsl", "view.glsl");
while (!glfwWindowShouldClose(window))
{
processInput(window);
computeShader.use();
computeShader.setInt("img", 0);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_3D, texId);
glDispatchCompute(100, 100, 100);
glMemoryBarrier(GL_SHADER_IMAGE_ACCESS_BARRIER_BIT);
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
viewShader.use();
viewShader.setInt("img", 0);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_3D, texId);
glm::mat4 model = glm::mat4(1.0f); // make sure to initialize matrix to identity matrix first
glm::mat4 view = glm::mat4(1.0f);
glm::mat4 projection = glm::mat4(1.0f);
model = glm::rotate(model, (float)glfwGetTime(), glm::vec3(0.5f, 1.0f, 0.0f));
view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));
projection = glm::perspective(glm::radians(45.0f), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
unsigned int modelLoc = glGetUniformLocation(viewShader.ID, "model");
unsigned int viewLoc = glGetUniformLocation(viewShader.ID, "view");
unsigned int projLoc = glGetUniformLocation(viewShader.ID, "projection");
glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));
// render cube
glBindVertexArray(cube.VAO);
glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, nullptr);
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwTerminate();
return 0;
}
void processInput(GLFWwindow* window)
{
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
}
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
glViewport(0, 0, width, height);
}
compute.glsl:
#version 430
layout(local_size_x=1, local_size_y=1, local_size_z=1) in;
layout(rgba8_snorm, binding=0) uniform image3D img;
uniform vec3 position;
void main()
{
ivec3 voxel_coord = ivec3(gl_WorkGroupID);
imageStore(img, voxel_coord, vec4(1, 1, 0, 1));
}
coords.glsl（顶点着色器）：
#version 430 core
layout (location = 0) in vec3 aPos;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main()
{
gl_Position = projection * view * model * vec4(aPos, 1.0f);
}
view.glsl（片段着色器）：
#version 430 core
out vec4 FragColor;
layout(rgba8_snorm, binding=0) uniform image3D img;
void main()
{
FragColor = imageLoad(img, ivec3(3,5,7));
}
原来我错过了对 glBindImageTexture 的调用 - 我认为为了将我的纹理绑定到着色器的图像变量，我需要设置制服并调用 glActiveTexture+glBindTexture 但似乎只需要 glBindImageTexture。
我替换了：
computeShader.setInt("img", 0);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_3D, texId)
与：
glBindImageTexture(0, texId, 0, true, 0, GL_WRITE_ONLY, GL_RGBA16);
我正在尝试使用计算着色器进行三维物理模拟，但无法将任何内容存储到我的 3D 纹理中。我的着色器编译成功，但是当从 3D 纹理中读回任何值时，我得到一个零向量。我之前也没有使用过计算着色器，所以我不确定我是否正确地分配了工作负载以实现我想要的。
我已经在此处的一个小示例中隔离了问题。基本上 compute.glsl 着色器具有统一的 image3D 并使用 imageStore 将 vec4(1,1,0,1) 写入 gl_WorkGroupID。在 C++ 中，我创建了一个 100x100x100 的 3D 纹理并将其绑定到着色器的制服，然后调用 glDispatchCompute(100,100,100) - 据我所知，这将创建 1,000,000 jobs/shader 次调用，纹理中的每个坐标调用一次。在我的 view.glsl 片段着色器中，我读取了一个随机坐标的值（在本例中为 (3,5,7)）并输出它。我用这个阴影一个立方体对象。
我尝试过的所有操作都会导致输出黑色立方体：
这是我的代码（我一直在关注 learnopengl.com，所以除了我扩展了着色器 class 来处理计算着色器之外，它基本上是相同的样板内容）：
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <stb_image.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <learnopengl/shader_m.h>
#include <iostream>
void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow* window);
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
struct vaoinfo
{
unsigned int VBO, VAO, EBO;
vaoinfo() : VAO(0), VBO(0), EBO(0)
{}
};
void create_vao(vaoinfo& info)
{
glGenVertexArrays(1, &info.VAO);
glGenBuffers(1, &info.VBO);
glGenBuffers(1, &info.EBO);
}
void init_vao(vaoinfo& info, float* vertices, int num_vertices, int* indices, int num_indices)
{
glGenVertexArrays(1, &info.VAO);
glGenBuffers(1, &info.VBO);
glGenBuffers(1, &info.EBO);
glBindVertexArray(info.VAO);
glBindBuffer(GL_ARRAY_BUFFER, info.VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(float) * num_vertices, vertices, GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, info.EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(int) * num_indices, indices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
glBindVertexArray(0);
}
int main()
{
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
if (window == NULL)
{
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
vaoinfo cube;
create_vao(cube);
glm::vec3 c(0.5, 0.5, 0.5);
float verts[24] =
{
c.x, -c.y, c.z,
c.x, c.y, c.z,
-c.x, c.y, c.z,
-c.x, -c.y, c.z,
c.x, -c.y, -c.z,
c.x, c.y, -c.z,
-c.x, c.y, -c.z,
-c.x, -c.y, -c.z,
};
int indices[36] =
{
7, 4, 5,
5, 6, 7,
3, 0, 1,
1, 2, 3,
2, 6, 7,
7, 3, 2,
1, 5, 4,
4, 0, 1,
7, 4, 0,
0, 3, 7,
6, 5, 1,
1, 2, 6
};
init_vao(cube, verts, 24, indices, 36);
// Create a 3D texture
unsigned int texId;
glGenTextures(1, &texId);
glBindTexture(GL_TEXTURE_3D, texId);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexImage3D(GL_TEXTURE_3D, 0, GL_RGBA8_SNORM, 100, 100, 100, 0, GL_RGBA, GL_FLOAT, nullptr);
// Create shaders
Shader computeShader("compute.glsl");
Shader viewShader("coords.glsl", "view.glsl");
while (!glfwWindowShouldClose(window))
{
processInput(window);
computeShader.use();
computeShader.setInt("img", 0);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_3D, texId);
glDispatchCompute(100, 100, 100);
glMemoryBarrier(GL_SHADER_IMAGE_ACCESS_BARRIER_BIT);
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
viewShader.use();
viewShader.setInt("img", 0);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_3D, texId);
glm::mat4 model = glm::mat4(1.0f); // make sure to initialize matrix to identity matrix first
glm::mat4 view = glm::mat4(1.0f);
glm::mat4 projection = glm::mat4(1.0f);
model = glm::rotate(model, (float)glfwGetTime(), glm::vec3(0.5f, 1.0f, 0.0f));
view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));
projection = glm::perspective(glm::radians(45.0f), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
unsigned int modelLoc = glGetUniformLocation(viewShader.ID, "model");
unsigned int viewLoc = glGetUniformLocation(viewShader.ID, "view");
unsigned int projLoc = glGetUniformLocation(viewShader.ID, "projection");
glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));
// render cube
glBindVertexArray(cube.VAO);
glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, nullptr);
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwTerminate();
return 0;
}
void processInput(GLFWwindow* window)
{
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
}
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
glViewport(0, 0, width, height);
}
compute.glsl:
#version 430
layout(local_size_x=1, local_size_y=1, local_size_z=1) in;
layout(rgba8_snorm, binding=0) uniform image3D img;
uniform vec3 position;
void main()
{
ivec3 voxel_coord = ivec3(gl_WorkGroupID);
imageStore(img, voxel_coord, vec4(1, 1, 0, 1));
}
coords.glsl（顶点着色器）：
#version 430 core
layout (location = 0) in vec3 aPos;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main()
{
gl_Position = projection * view * model * vec4(aPos, 1.0f);
}
view.glsl（片段着色器）：
#version 430 core
out vec4 FragColor;
layout(rgba8_snorm, binding=0) uniform image3D img;
void main()
{
FragColor = imageLoad(img, ivec3(3,5,7));
}
原来我错过了对 glBindImageTexture 的调用 - 我认为为了将我的纹理绑定到着色器的图像变量，我需要设置制服并调用 glActiveTexture+glBindTexture 但似乎只需要 glBindImageTexture。
我替换了：
computeShader.setInt("img", 0);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_3D, texId)
与：
glBindImageTexture(0, texId, 0, true, 0, GL_WRITE_ONLY, GL_RGBA16);