OpenGL 4.3 错误地将第 4 个纹理坐标映射到与第 3 个纹理坐标相同的位置

OpenGL 4.3 incorrectly mapping 4th texture coordinate to the same poisition as the 3rd texture coordinate

本文关键字:坐标 纹理 位置 映射 错误 OpenGL      更新时间:2023-10-16

当我运行这个程序时,它似乎只将我的纹理映射到直角三角形的 3 条边(我的顶点数组中的前 3 个点(,并且完全错过了第四个,因为当我更改该位时,图像中没有任何变化。 https://i.stack.imgur.com/d8loL.jpg 这里是当前输出作为顶部图像, 以及作为第二个图像的预期输出。当我在着色器中只用一种颜色对它进行纹理处理时,它的映射很好,有纹理,它似乎仍然在绘制一个正方形,但是当它应该映射到右上角时,它映射到左上角。

Vertex vertices[] = {
//Position                 //Colour
vec3(-0.5f, 0.5f, 0.f),        vec3(1.f, 0.f, 0.f),    vec2(0.f, 1.f), //Top left
vec3(-0.5f, -0.5f, 0.f),       vec3(0.f, 1.f, 0.f),    vec2(0.f, 0.f), //Bottom Left
vec3(0.5f, -0.5f, 0.f),        vec3(0.f, 0.f, 1.f),    vec2(1.f, 0.f), //Bottom Right
vec3(0.5f, 0.5f, 0.f),         vec3(1.f, 1.f, 1.f),    vec2(1.f, 1.f)  //Top Right
};
unsigned int numOfVertices = sizeof(vertices) / sizeof(Vertex);
GLuint indices[] = {
0,1,2,
3,0,2
};
unsigned numOfIndices = sizeof(indices) / sizeof(GLint);
void updateInput(GLFWwindow* window) {
if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, GL_TRUE);
}
int main() {
//INIT GLFW
glfwInit();
Wrapper mainWrapper = Wrapper();
Shader *mainShader = new Shader(vs_source.c_str(), fs_source.c_str());
GLuint VAO;
glGenVertexArrays(1, &VAO);
glBindVertexArray(VAO);
GLuint VBO;
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
GLuint EBO;
glGenBuffers(1, &EBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
glVertexAttribPointer(0,4, GL_FLOAT, GL_FALSE, sizeof(Vertex),(GLvoid*)offsetof(Vertex, position));
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)offsetof(Vertex, color));
glEnableVertexAttribArray(1);
glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)offsetof(Vertex, texcoord));
glEnableVertexAttribArray(2);
glBindVertexArray(0);
//TEXTURE INIT
int image_width = 0;
int image_height = 0;
unsigned char* image = SOIL_load_image("images/super-meat-boy.png", &image_width, &image_height, NULL, SOIL_LOAD_RGBA);
GLuint texture0;
glGenTextures(1, &texture0);
glBindTexture(GL_TEXTURE_2D, texture0);
glGenerateMipmap(GL_TEXTURE_2D);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
if (image) {
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image_width, image_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, image);
glGenerateMipmap(GL_TEXTURE_2D);
std::cout << "IMAGE LOADED";
}
else {
std::cout << "Error loading image";
}
//Clean up, needed when stuff done with texture
glActiveTexture(0);
glBindTexture(GL_TEXTURE_2D, 0);
SOIL_free_image_data(image);
//MAIN LOOP
while (!glfwWindowShouldClose(mainWrapper.getWindow())) {
//UPDATE INPUT
updateInput(mainWrapper.getWindow());
glfwPollEvents();
//UPDATE
//DRAW------
//clear
glClearColor(0.f,0.f,0.f,1.f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
//draw
glUseProgram(mainShader->myProgram);
//activate texture
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture0);
glBindVertexArray(VAO);
glDrawElements(GL_TRIANGLES, numOfIndices, GL_UNSIGNED_INT, 0);
//END DRAW
glfwSwapBuffers(mainWrapper.getWindow());
glFlush();
}
//END OF PROGRAM
glfwDestroyWindow(mainWrapper.getWindow());
delete mainShader;
glfwTerminate();
return 0;
}
#version 440
layout (location = 0) in vec3 vertex_position;
layout (location = 1) in vec3 vertex_color;
layout (location = 2) in vec3 vertex_texcoord;
out vec3 vs_position;
out vec3 vs_color;
out vec2 vs_texcoord;
void main() {
vs_position = vertex_position;
vs_color = vertex_color;
vs_texcoord = vec2(vertex_texcoord.x, vertex_texcoord.y * -1.f);
gl_Position = vec4(vertex_position, 1.f);
}
#version 440
in vec3 vs_position;
in vec3 vs_color;
in vec2 vs_texcoord;
out vec4 fs_color;
uniform sampler2D texture0;
void main() {
fs_color = vec4(vs_color, 1.f);
fs_color = texture(texture0, vs_texcoord);
}

glVertexAttribPointer的第二个参数必须是顶点缓冲区中属性的元组大小(组件数(。

顶点坐标有 3 个分量 x、y、z。颜色属性也有 3 个组成部分(红色、绿色、蓝色(。纹理坐标有 2 个分量 u 和 v:

glVertexAttribPointer(0, 
3, // 3 instead of 4
GL_FLOAT, GL_FALSE, sizeof(Vertex),(GLvoid*)offsetof(Vertex, position));
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 
3, // 3 instead of 4
GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)offsetof(Vertex, color));
glEnableVertexAttribArray(1);
glVertexAttribPointer(2,
3, // 2 instead of 3
GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)offsetof(Vertex, texcoord));
glEnableVertexAttribArray(2);

纹理坐标元组大小的参数 3 会导致您超出界限访问索引为 3 的顶点坐标的顶点缓冲区。

在我的glVertexAttribPointer中,它的大小不正确。此后,我将顶点更改为 vec2、vec3、vec2,并相应地更改了大小。