【发布时间】：2021-04-04 20:31:58
【问题描述】：
所以我一直在尝试编写一个在屏幕上显示四边形的基本程序。 无论我做什么，它都只会显示黑屏。 我检查了图书馆，一切都已链接。 我检查了代码，一切似乎都很好（但我知道它不是） 但最荒谬的是：当我将一个看似相同的程序粘贴到同一台计算机上的同一个项目中时，它可以工作，而当我再次粘贴时，它又不能工作。
顺便说一句 - 我还尝试通过在线文本差异查找器运行它......它表明它是同一件事。
原始代码（不工作）：
#include <iostream>
#include <fstream>
#include <string>
#include "GL/glew.h"
#include "GLFW/glfw3.h"
static unsigned int CompileShader(const std::string& source, unsigned int type) {
unsigned int shader = glCreateShader(type);
const char* src = source.c_str();
glShaderSource(shader, 1, &src, nullptr);
glCompileShader(shader);
int result;
glGetShaderiv(shader, GL_COMPILE_STATUS, &result);
// i - int
// v - vector
if (result == GL_FALSE) {
std::cout << "Shader cannot be compiled.\n" << (type == GL_VERTEX_SHADER ? "vertex s." : "fragments.") << "\n";
int length;
glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &length);
char* message = (char*)_malloca(length * sizeof(char));
glGetShaderInfoLog(shader, length, &length, message);
std::cout << message << "\n";
glDeleteShader(shader);
}
return shader;
}
static int CreateShader(const std::string& vShader, const std::string& fShader) {
unsigned int program = glCreateProgram();
unsigned int vs = CompileShader(vShader, GL_VERTEX_SHADER);
unsigned int fs = CompileShader(fShader, GL_FRAGMENT_SHADER);
glAttachShader(program, vs);
glAttachShader(program, fs);
glLinkProgram(program);
glValidateProgram(program);
glDeleteShader(vs);
glDeleteShader(fs);
return program;
}
int main() {
glfwInit();
GLFWwindow* window = glfwCreateWindow(1280, 720, "CITY ENGINE", 0, 0);
glfwMakeContextCurrent(window);
glewInit();
float vertices[8] = { 0.1f, 0.1f,
-0.1f, 0.1f,
-0.1f, -0.1f,
0.1f, -0.1f };
unsigned int varray;
glGenVertexArrays(1, &varray);
glBindVertexArray(varray);
unsigned int vbuffer;
glGenBuffers(1, &vbuffer);
glBindBuffer(vbuffer, GL_ARRAY_BUFFER);
glBufferData(GL_ARRAY_BUFFER, 4 * 2 * sizeof(float), vertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0);
glEnableVertexAttribArray(0);
unsigned int indices[6] = { 0, 1, 2,
2, 3, 0 };
unsigned int ibuffer;
glGenBuffers(1, &ibuffer);
glBindBuffer(ibuffer, GL_ELEMENT_ARRAY_BUFFER);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, 6 * sizeof(unsigned int), indices, GL_STATIC_DRAW);
unsigned int shader = CreateShader(
"#version 330 core\n"
"\n"
"layout(location = 0) in vec4 position;\n"
"\n"
"void main()\n"
"{\n"
"gl_Position = position;\n"
"};\n"
,
"#version 330 core\n"
"\n"
"layout(location = 0) out vec4 color;\n"
"uniform vec4 u_Color;\n"
"\n"
"void main()\n"
"{\n"
" color = u_Color;\n"
"};\n"
);
glUseProgram(shader);
int location = glGetUniformLocation(shader, "u_Color");
glUniform4f(location, 0.3f, 0.3f, 1.0f, 1.0f);
glBindVertexArray(0);
glUseProgram(0);
glBindBuffer(0, GL_ARRAY_BUFFER);
glBindBuffer(0, GL_ELEMENT_ARRAY_BUFFER);
while (!glfwWindowShouldClose(window)) {
glClear(GL_COLOR_BUFFER_BIT);
glBindVertexArray(varray);
glBindBuffer(ibuffer, GL_ELEMENT_ARRAY_BUFFER);
glUseProgram(shader);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr);
glfwSwapBuffers(window);
glfwPollEvents();
}
}
工作的人：
#include <iostream>
#include <fstream>
#include <string>
#include "GL/glew.h"
#include "GLFW/glfw3.h"
static unsigned int CompileShader(const std::string& source, unsigned int type) {
unsigned int shader = glCreateShader(type);
const char* src = source.c_str();
glShaderSource(shader, 1, &src, nullptr);
glCompileShader(shader);
int result;
glGetShaderiv(shader, GL_COMPILE_STATUS, &result);
// i - int
// v - vector
if (result == GL_FALSE) {
std::cout << "Shader cannot be compiled.\n" << (type == GL_VERTEX_SHADER ? "vertex s." : "fragments.") << "\n";
int length;
glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &length);
char* message = (char*)_malloca(length * sizeof(char));
glGetShaderInfoLog(shader, length, &length, message);
std::cout << message << "\n";
glDeleteShader(shader);
}
return shader;
}
static int CreateShader(const std::string& vShader, const std::string& fShader) {
unsigned int program = glCreateProgram();
unsigned int vs = CompileShader(vShader, GL_VERTEX_SHADER);
unsigned int fs = CompileShader(fShader, GL_FRAGMENT_SHADER);
glAttachShader(program, vs);
glAttachShader(program, fs);
glLinkProgram(program);
glValidateProgram(program);
glDeleteShader(vs);
glDeleteShader(fs);
return program;
}
int main() {
glfwInit();
GLFWwindow* window;
window = glfwCreateWindow(640, 480, "Modern OpenGL Test", NULL, NULL);
glfwMakeContextCurrent(window);
glewInit();
float vertices[] = {
-0.5f, -0.5f,
0.5f, -0.5f,
0.5f, 0.5f,
-0.5f, 0.5f,
};
unsigned int indices[] = {
0, 1, 2,
2, 3, 0
};
unsigned int varray;
glGenVertexArrays(1, &varray);
glBindVertexArray(varray);
unsigned int vb;
glGenBuffers(1, &vb);
glBindBuffer(GL_ARRAY_BUFFER, vb);
glBufferData(GL_ARRAY_BUFFER, 4 * 2 * sizeof(float), vertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0);
glEnableVertexAttribArray(0);
unsigned int ib;
glGenBuffers(1, &ib);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ib);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, 6 * sizeof(unsigned int), indices, GL_STATIC_DRAW);
unsigned int shaders = CreateShader(
"#version 330 core\n"
"\n"
"layout(location = 0) in vec4 position;\n"
"\n"
"void main()\n"
"{\n"
" gl_Position = position;\n"
"};\n"
,
"#version 330 core\n"
"\n"
"layout(location = 0) out vec4 color;\n"
"\n"
"uniform vec4 u_Color;\n"
"\n"
"void main()\n"
"{\n"
" color = u_Color;\n"
"};\n");
glUseProgram(shaders);
int location = glGetUniformLocation(shaders, "u_Color");
glUniform4f(location, 0.3f, 0.3f, 1.0f, 1.0f);
glBindVertexArray(0);
glUseProgram(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
while (!glfwWindowShouldClose(window)) {
glClear(GL_COLOR_BUFFER_BIT);
glBindVertexArray(varray);
glUseProgram(shaders);
glBindBuffer(ib, GL_ELEMENT_ARRAY_BUFFER);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr);
glfwSwapBuffers(window);
glfwPollEvents();
}
glDeleteProgram(shaders);
glfwTerminate();
}
【问题讨论】：