OpenGL红宝书例3.1 -- glBufferSubData使用
- 代码实现
1.1 C++部分
GLFWwindow *window;
GLuint shader_program;
GLuint VAO;
void init()
{
static const GLfloat positions[] =
{
-1.0f, -1.0f, 0.0f, 1.0f,
1.0f, -1.0f, 0.0f, 1.0f,
1.0f, 1.0f, 0.0f, 1.0f,
-1.0f, 1.0f, 0.0f, 1.0f,
};
static const GLfloat colors[] =
{
1.0f, 0.0f, 0.0f,
0.0f, 1.0f, 0.0f,
0.0f, 0.0f, 1.0f,
1.0f, 1.0f, 1.0f,
};
glGenVertexArrays(1, &VAO);
glBindVertexArray(VAO);
GLuint buffer;
glGenBuffers(1, &buffer);
glBindBuffer(GL_ARRAY_BUFFER, buffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(positions)+sizeof(colors), nullptr, GL_STATIC_DRAW);
glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(positions), positions);
glBufferSubData(GL_ARRAY_BUFFER, sizeof(positions), sizeof(colors), colors);
shader_program = CreateShaderProgram();
GLuint vec_shader = LoadShader("triangles.vert", GL_VERTEX_SHADER);
GLuint fs_shader = LoadShader("triangles.frag", GL_FRAGMENT_SHADER);
LinkShader(shader_program, vec_shader, fs_shader, 0);
glUseProgram(shader_program);
glBindVertexArray(0);
glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
}
void display()
{
while (!glfwWindowShouldClose(window))
{
/* Render here */
glClear(GL_COLOR_BUFFER_BIT);
glBindVertexArray(VAO);
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, (void *)0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 0, (void *)0);
glEnableVertexAttribArray(1);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glBindVertexArray(0);
glfwSwapBuffers(window);
/* Poll for and process events */
glfwPollEvents();
}
glfwTerminate();
glDeleteProgram(shader_program);
}
int CALLBACK WinMain( HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nShowCmd )
{
if(!glfwInit())
return -1;
glfwWindowHint(GLFW_SAMPLES, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
window = glfwCreateWindow(512, 512, "Hello World", NULL, NULL);
if(!window)
{
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
// Initialize GLEW
glewExperimental = true; // Needed for core profile
if( GLEW_OK != glewInit())
return -1;
init();
display();
return 0;
}
1.2 代码实现 -- shader 部分
// vexter
#version 430 core
layout (location = 0) in vec4 poistion;
layout (location = 1) in vec3 color;
out vec3 out_color;
void main()
{
gl_Position = poistion;
out_color = color;
}
// fragment
#version 430 core
// Ouput data
out vec4 color;
in vec3 out_color;
void main()
{
color = vec4(out_color, 1.0);
}