[英]OpenGL - Hello triangle not showing up
我在這里有我的OpenGL-Hello Triangle演示,但我無法使其工作。 有人知道問題可能在哪里嗎? 我可以編譯並運行代碼,但三角形不顯示。 它只會打開帶有灰色背景的窗口。
#include <glew/glew.h>
#include <glfw/glfw3.h>
#include <stdio.h>
#include <stdlib.h>
int main() {
if (!glfwInit()) {
fprintf(stderr, "Failed to initialize GLFW\n");
return -1;
}
GLFWwindow* window = glfwCreateWindow(800, 800, "Anton Tutorials - Hello Triangle", NULL, NULL);
if (window == NULL) {
fprintf(stderr, "Failed to open GLFW window.\n");
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glewExperimental = GL_TRUE; // Needed in core profile
const GLenum err = glewInit();
if (err != GLEW_OK) {
fprintf(stderr, "Failed to initialize GLEW\n");
fprintf(stderr, "Error: %s\n", glewGetErrorString(err));
return -1;
}
// Enable depth-testing
glEnable(GL_DEPTH_TEST);
// Depth-testing interprets a smaller value as "closer"
glDepthFunc(GL_LESS);
//Defining vertices for triangle
GLfloat points[] = {
0.0f, 0.5f, 0.0f,
0.5f, -0.5f, 0.0f,
-0.5f, -0.5f, 0.0f
};
//Vertex buffer object creation
GLuint vbo = 0;
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(points), points, GL_STATIC_DRAW);
//Vertex attribute object creation
GLuint vao = 0;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
glDisableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, NULL);
//Loading shaders - Vertex shader
const char* vertex_shader =
"#version 410\n"
"in vec3 vp; "
"void main() {"
" gl_Position = vec4 (vp, 1.0);"
" }";
GLuint vs = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vs, 1, &vertex_shader, NULL);
glCompileShader(vs);
//Loading shaders - Fragment shader
const char* fragment_shader =
"#version 410\n"
"out vec4 frag_colour; "
"void main() {"
" frag_colour = vec4 (0.5, 0.0, 0.5, 1.0);"
" }";
GLuint fs = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fs, 1, &fragment_shader, NULL);
glCompileShader(fs);
//Attach shaders
GLuint shader_programme = glCreateProgram();
glAttachShader(shader_programme, fs);
glAttachShader(shader_programme, vs);
glLinkProgram(shader_programme);
//RenderLoop
while (!glfwWindowShouldClose(window))
{
glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glUseProgram(shader_programme);
glBindVertexArray(vao);
glDrawArrays(GL_TRIANGLES, 0, 3);
glfwPollEvents();
glfwSwapBuffers(window);
}
glfwTerminate();
return 0;
}
您需要啟用“ vp”屬性。
在代碼的前面,您這樣說:
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, NULL);
如果您的vp着色器變量的布局位置發生了更改,那么這現在可能不再有效。
這樣做會更好:
GLint vpAttr = glGetAttribLocation(shader_programme, "vp");
glVertexAttribPointer(vpAttr, 3, GL_FLOAT, GL_FALSE, 0, NULL);
然后啟用屬性:
glEnableVertexAttribArray(vpAttr);
否則,您應該在頂點着色器中顯式設置vp的布局位置,以便可以放心地使用0:
"layout (location=0) in vec3 vp;"
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