Question

How to draw a triangle using OpenGL if the GPU manufacturer write a basic shader for you in C

Answer 1

#include <GL/glew.h>
#include <GLFW/glfw3.h>

#include <stdio.h>

// You might or might not see the triangle

int main(void)
{
    if (!glfwInit()) {
        printf("glfwInit() Error!");
        return -1;
    }

    GLFWwindow* window = glfwCreateWindow(640, 480, "Window Title", NULL, NULL);
    if (!window) {
        glfwTerminate();
        return -1;
    }

    glfwMakeContextCurrent(window);

    if (glewInit() != GLEW_OK) {
        printf("glewInit() Error!");
        return -1;
    }

    float triangle_positions[6] = {
        -0.4f, -0.4f,
         0.0f,  0.4f,
         0.4f, -0.4f
    };
 
    unsigned int buffer;
    glGenBuffers(1, &buffer);
    glBindBuffer(GL_ARRAY_BUFFER, buffer);
    glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), triangle_positions, GL_STATIC_DRAW);
    
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0);

    glBindBuffer(GL_ARRAY_BUFFER, 0);

    glClearColor(0.5f, 0.6f, 0.7f, 1.0f);

    while (!glfwWindowShouldClose(window)) {
        glClear(GL_COLOR_BUFFER_BIT);

        glDrawArrays(GL_TRIANGLES, 0, 3);
        
        glfwSwapBuffers(window);

        glfwPollEvents();
    }

    glfwTerminate();

    return 0;
}



/*
run:


*/

 

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