如何使用sf:: shader::setUniform在GLSL着色器中设置统一mat4 ?

Question

我尝试使用着色器绘制矩形纹理，遵循本教程，这是我的代码:

main.cpp:

#define GLM_ENABLE_EXPERIMENTAL
#define GLEW_STATIC
#include<GL/glew.h>
#include<SFML/Graphics.hpp>
#include<SFML/OpenGL.hpp>
#include"../include/glm/glm.hpp"
#include"../include/glm/gtx/transform.hpp"
#include"../include/glm/gtc/type_ptr.hpp"
#include<iostream>
float vertices[] = {
// positions          // texture coords
0.5f,  0.5f, 0.0f,   1.0f, 1.0f, // top right
0.5f, -0.5f, 0.0f,   1.0f, 0.0f, // bottom right
-0.5f, -0.5f, 0.0f,   0.0f, 0.0f, // bottom left
-0.5f,  0.5f, 0.0f,   0.0f, 1.0f  // top left 
};
int main(){
sf::ContextSettings set;
set.depthBits = 24;
sf::RenderWindow window(sf::VideoMode(800, 600), "Window", sf::Style::Default, set);
window.setActive(true);
glewInit();
glewExperimental = GL_TRUE;
glEnable(GL_TEXTURE_2D);
sf::Image im;
im.loadFromFile("texture.jpg");
im.flipVertically();
sf::Texture tex1;
tex1.loadFromImage(im);
sf::Shader shader;
shader.loadFromFile(
"vertex.txt",
"fragment.txt"
);
shader.setUniform("tex1", tex1);
glm::mat4 transform = glm::mat4(1.f);
transform = glm::translate(transform, glm::vec3(0.3f, 0.3f, 0.f));
shader.setUniform("transform", glm::value_ptr(transform)); // !!!
sf::Shader::bind(&shader);
unsigned int VBO;
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
unsigned int VAO;
glGenVertexArrays(1, &VAO);
glBindVertexArray(VAO);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(0 * sizeof(float)));
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1); 
glViewport(0.f, 0.f, 800.f, 600.f);
glClearColor(0.f, 100.f, 150.f, 0.f);
while(window.isOpen()){
sf::Event event;
while(window.pollEvent(event)){
if (event.type == sf::Event::Closed){
window.close();
}
}
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glDrawArrays(GL_QUADS, 0, 4);
window.display();
}
}

vertex.txt::

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec2 aTexCoord;
out vec2 TexCoord;

uniform mat4 transform;
void main()
{
gl_Position = transform * vec4(aPos, 1.0f);
TexCoord = vec2(aTexCoord.x, aTexCoord.y);
}

但是它只是画出没有矩形的透明颜色。

有趣的部分是，没有转换，它工作得很好-如果gl_Position = transform * vec4(aPos, 1.0f);线改变为gl_Position = vec4(aPos, 1.0f);，它绘制未转换的矩形与纹理预期。所以我猜，这是设置统一的问题，但它会很奇怪，至少纹理设置没有任何问题。我做错了什么?

Answer 1

sf::Shader对sf::Glsl::Mat4类型有一个重载的setUniform方法。需要创建一个sf::Glsl::Mat4对象。可以从浮点数数组中创建:

sf::Glsl::Mat4 sfTransform(glm::value_ptr(transform));
shader.setUniform("transform", sfTransform);