[英]White Screen(OpenGL)
我是 OpenGL 的新手,我想用我的着色器在屏幕上绘制一个简单的三角形。 我设置了缓冲区并编写了着色器,但它似乎不起作用。 它给出了白屏,我试图用 glGenBuffer 更改 glCreateBuffer 并且屏幕变成了黑屏。 我想在一个名为 createAndCompileShader(...) 的 function 中创建和编译着色器,缓冲区在主 function 中定义。
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <string>
#include <iostream>
static unsigned int createAndCompileShader(const char* vertexShader, const char* fragmentShader) {
unsigned int fragmentShaderr = glCreateShader(GL_FRAGMENT_SHADER);
unsigned int vertexShaderr = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShaderr, 1, &vertexShader, NULL);
glShaderSource(fragmentShaderr, 1, &fragmentShader, NULL);
glCompileShader(vertexShaderr);
glCompileShader(fragmentShaderr);
unsigned int program = glCreateProgram();
glAttachShader(program, vertexShaderr);
glAttachShader(program, fragmentShaderr);
glLinkProgram(program);
return program;
}
int main(void)
{
GLFWwindow* window;
/* Initialize the library */
if (!glfwInit())
return -1;
/* Create a windowed mode window and its OpenGL context */
window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
if (!window)
{
glfwTerminate();
return -1;
}
/* Make the window's context current */
glfwMakeContextCurrent(window);
float vertexPositions[6] = {
-0.5, -0.5,
0.0, 0.5,
0.5, -0.5
};
const char* vertexShader = "#version 330 core\n"
"layout(location = 0) in vec4 position;\n"
"void main()\n"
"{\n"
"gl_Position = position;\n"
"}\n";
const char* fragementShader = "#version 330 core\n"
"layout(location = 0) in vec4 position;\n"
"void main()\n"
"{\n"
"color = vec4(1.0, 0.0, 0.0, 1.0);\n"
"}\n";
unsigned int program = createAndCompileShader(vertexShader, fragementShader);
glUseProgram(program);
unsigned int buffer;
glGenBuffers(1, &buffer);
//glCreateBuffers(1, &buffer);
glBindBuffer(GL_ARRAY_BUFFER, buffer);
glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), vertexPositions, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float)*2 , 0);
//std::string vertexShader;
//std::string fragmentShader;
/* Loop until the user closes the window */
while (!glfwWindowShouldClose(window))
{
/* Render here */
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0 ,3);
/*glBegin(GL_TRIANGLES);
glVertex2f(-0.5, -0.5);
glVertex2f( 0.0, 0.5);
glVertex2f( 0.5, -0.5);
glEnd();*/
/* Swap front and back buffers */
glfwSwapBuffers(window);
/* Poll for and process events */
glfwPollEvents();
}
glDeleteProgram(program);
glfwTerminate();
return 0;
}
GLSL 3.30 中未提供片段着色器输入布局位置限定符。 您必须切换到 GLSL 4.10 或删除片段着色器中的布局位置:
layout(location = 0) in vec4 position;
in vec4 position;
此外,您错过了片段着色器 output color
的规范。
#version 330 core
in vec4 position;
out vec4 color;
void main()
{
color = vec4(1.0, 0.0, 0.0, 1.0);
}
我建议使用Raw string liters :
const char* fragementShader = R"(#version 330 core
in vec4 position;
out vec4 color;
void main()
{
color = vec4(1.0, 0.0, 0.0, 1.0);
})";
检查shader编译是否成功,程序object是否链接成功。
如果着色器编译成功,可以通过glGetShaderiv
和参数GL_COMPILE_STATUS
检查。
如果程序链接成功,可以通过glGetProgramiv
和参数GL_LINK_STATUS
。
(请参阅此问题的答案。)
如果使用核心配置文件 OpenGL Context,则默认的Vertex Array Object无效。 创建一个命名的 VAO:
unsigned int VAO;
glCreateVertexArrays(1, &VAO);
glBindVertexArray(VAO);
unsigned int buffer;
glGenBuffers(1, &buffer);
glBindBuffer(GL_ARRAY_BUFFER, buffer);
glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), vertexPositions, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float)*2 , 0);
GLEW必须由glewInit()
初始化。 请参阅初始化 GLEW :
glfwMakeContextCurrent(window);
glewInit();
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