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space-war/libs/glfw/examples/triangle-opengles.c

171 lines
5.1 KiB
C

//========================================================================
// OpenGL ES 2.0 triangle example
// Copyright (c) Camilla Löwy <elmindreda@glfw.org>
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software. If you use this software
// in a product, an acknowledgment in the product documentation would
// be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not
// be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
// distribution.
//
//========================================================================
#define GLAD_GLES2_IMPLEMENTATION
#include <glad/gles2.h>
#define GLFW_INCLUDE_NONE
#include <GLFW/glfw3.h>
#include "linmath.h"
#include <stdlib.h>
#include <stddef.h>
#include <stdio.h>
typedef struct Vertex
{
vec2 pos;
vec3 col;
} Vertex;
static const Vertex vertices[3] =
{
{ { -0.6f, -0.4f }, { 1.f, 0.f, 0.f } },
{ { 0.6f, -0.4f }, { 0.f, 1.f, 0.f } },
{ { 0.f, 0.6f }, { 0.f, 0.f, 1.f } }
};
static const char* vertex_shader_text =
"#version 100\n"
"precision mediump float;\n"
"uniform mat4 MVP;\n"
"attribute vec3 vCol;\n"
"attribute vec2 vPos;\n"
"varying vec3 color;\n"
"void main()\n"
"{\n"
" gl_Position = MVP * vec4(vPos, 0.0, 1.0);\n"
" color = vCol;\n"
"}\n";
static const char* fragment_shader_text =
"#version 100\n"
"precision mediump float;\n"
"varying vec3 color;\n"
"void main()\n"
"{\n"
" gl_FragColor = vec4(color, 1.0);\n"
"}\n";
static void error_callback(int error, const char* description)
{
fprintf(stderr, "GLFW Error: %s\n", description);
}
static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
glfwSetWindowShouldClose(window, GLFW_TRUE);
}
int main(void)
{
glfwSetErrorCallback(error_callback);
if (!glfwInit())
exit(EXIT_FAILURE);
glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
glfwWindowHint(GLFW_CONTEXT_CREATION_API, GLFW_EGL_CONTEXT_API);
GLFWwindow* window = glfwCreateWindow(640, 480, "OpenGL ES 2.0 Triangle (EGL)", NULL, NULL);
if (!window)
{
glfwWindowHint(GLFW_CONTEXT_CREATION_API, GLFW_NATIVE_CONTEXT_API);
window = glfwCreateWindow(640, 480, "OpenGL ES 2.0 Triangle", NULL, NULL);
if (!window)
{
glfwTerminate();
exit(EXIT_FAILURE);
}
}
glfwSetKeyCallback(window, key_callback);
glfwMakeContextCurrent(window);
gladLoadGLES2(glfwGetProcAddress);
glfwSwapInterval(1);
GLuint vertex_buffer;
glGenBuffers(1, &vertex_buffer);
glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
const GLuint vertex_shader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
glCompileShader(vertex_shader);
const GLuint fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
glCompileShader(fragment_shader);
const GLuint program = glCreateProgram();
glAttachShader(program, vertex_shader);
glAttachShader(program, fragment_shader);
glLinkProgram(program);
const GLint mvp_location = glGetUniformLocation(program, "MVP");
const GLint vpos_location = glGetAttribLocation(program, "vPos");
const GLint vcol_location = glGetAttribLocation(program, "vCol");
glEnableVertexAttribArray(vpos_location);
glEnableVertexAttribArray(vcol_location);
glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE,
sizeof(Vertex), (void*) offsetof(Vertex, pos));
glVertexAttribPointer(vcol_location, 3, GL_FLOAT, GL_FALSE,
sizeof(Vertex), (void*) offsetof(Vertex, col));
while (!glfwWindowShouldClose(window))
{
int width, height;
glfwGetFramebufferSize(window, &width, &height);
const float ratio = width / (float) height;
glViewport(0, 0, width, height);
glClear(GL_COLOR_BUFFER_BIT);
mat4x4 m, p, mvp;
mat4x4_identity(m);
mat4x4_rotate_Z(m, m, (float) glfwGetTime());
mat4x4_ortho(p, -ratio, ratio, -1.f, 1.f, 1.f, -1.f);
mat4x4_mul(mvp, p, m);
glUseProgram(program);
glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat*) &mvp);
glDrawArrays(GL_TRIANGLES, 0, 3);
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwDestroyWindow(window);
glfwTerminate();
exit(EXIT_SUCCESS);
}