hello every one
i finally did it draw a triangle on the screen ,i want now to draw multi-shapes but i don't know where i must add a second vertex buffer ,
this is the code source :
#include <GL/glew.h>
// include GLEW and new version of GL on Windows
#define GLFW_DLL
#include <GL/glfw3.h> // GLFW helper library
#include <stdio.h>
int main () {
// start GL context and O/S window using the GLFW helper library
if (!glfwInit ()) {
fprintf (stderr, "ERROR: could not start GLFW3\n");
return 1;
}
// uncomment these lines if on Apple OS X
/*glfwWindowHint (GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint (GLFW_CONTEXT_VERSION_MINOR, 2);
glfwWindowHint (GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
glfwWindowHint (GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);*/
GLFWwindow* window = glfwCreateWindow (640, 480, "Hello Triangle", NULL, NULL);
if (!window) {
fprintf (stderr, "ERROR: could not open window with GLFW3\n");
glfwTerminate();
return 1;
}
glfwMakeContextCurrent (window);
// start GLEW extension handler
glewExperimental = GL_TRUE;
glewInit ();
// get version info
const GLubyte* renderer = glGetString (GL_RENDERER); // get renderer string
const GLubyte* version = glGetString (GL_VERSION); // version as a string
printf ("Renderer: %s\n", renderer);
printf ("OpenGL version supported %s\n", version);
// tell GL to only draw onto a pixel if the shape is closer to the viewer
glEnable (GL_DEPTH_TEST); // enable depth-testing
glDepthFunc (GL_LESS); // depth-testing interprets a smaller value as "closer"
/* OTHER STUFF GOES HERE NEXT */
float points[] = {
-0.5f, 0.5f, 0.0f,
-0.25f, -0.0f, 0.0f,
-0.75f, -0.0f, 0.0f,
};
float points01[] = { //the rictangele
0.25f, 0.25f, 0.0f,
0.75f, 0.25f, 0.0f,
0.75f, -0.25f, 0.0f,
0.25f, -0.25f, 0.0f
};
//create a vertex buffer and bind it for triangle
GLuint vbo = 0;
glGenBuffers (1, &vbo);
glBindBuffer (GL_ARRAY_BUFFER, vbo);
glBufferData (GL_ARRAY_BUFFER, 9 * sizeof (float), points, GL_STATIC_DRAW);
//create a vertex buffer and bind it for rectangle
GLuint vbo01=0;
glGenBuffers (1, &vbo01);
glBindBuffer (GL_ARRAY_BUFFER, vbo01);
glBufferData (GL_ARRAY_BUFFER, 12 * sizeof (float), points01, GL_STATIC_DRAW);
// Here we create a vertex attribute Object
GLuint vao = 0;
glGenVertexArrays (1, &vao);
glEnableVertexAttribArray (0);
glBindBuffer (GL_ARRAY_BUFFER, vbo);
glVertexAttribPointer (0, 3, GL_FLOAT, GL_FALSE, 0, NULL);
//second vattribute
GLuint vao01 = 0;
glGenVertexArrays (1, &vao01);
glEnableVertexAttribArray (1);
glBindBuffer (GL_ARRAY_BUFFER, vbo01);
glVertexAttribPointer (1, 3, GL_FLOAT, GL_FALSE, 0, NULL);
//shader parts
//vertex shader
const char* vertex_shader =
"#version 400\n"
"in vec3 vp;"
"void main () {"
" gl_Position = vec4 (vp, 1.0);"
"}";
//fragment shader
const char* fragment_shader =
"#version 400\n"
"out vec4 frag_colour;"
"void main () {"
" frag_colour = vec4 (0.8, 0.5, 0.5, 1.0);"
"}";
//load shader
GLuint vs = glCreateShader (GL_VERTEX_SHADER);
glShaderSource (vs, 1, &vertex_shader, NULL);
glCompileShader (vs);
//load fragment shader
GLuint fs = glCreateShader (GL_FRAGMENT_SHADER);
glShaderSource (fs, 1, &fragment_shader, NULL);
glCompileShader (fs);
//create the program
GLuint shader_programme = glCreateProgram ();
//attach the vertex shader and fragment shader to the program
glAttachShader (shader_programme, fs);
glAttachShader (shader_programme, vs);
//link the program
glLinkProgram (shader_programme);
//drawing
while (!glfwWindowShouldClose (window)) {
// wipe the drawing surface clear
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glUseProgram (shader_programme);
glBindVertexArray (vao);
// draw points 0-3 from the currently bound VAO with current in-use shader
glBindVertexArray (vao01);
glDrawArrays (GL_TRIANGLES, 1,3);
// draw points 0-3 from the currently bound VAO with current in-use shader
glDrawArrays (GL_QUADS,0,4);
// update other events like input handling
glfwPollEvents ();
// put the stuff we've been drawing onto the display
glfwSwapBuffers (window);
}
// close GL context and any other GLFW resources
glfwTerminate();
return 0;
}