animation.php

<?php

// https://open.gl/transformations

require 'bootstrap.php';

require 'vendor/autoload.php';
use \glm\vec3;
use \glm\mat4;
use Mammoth\Graphic\ImageLoader;
use Mammoth\Math\Angle;
use Mammoth\Math\Matrix;
use Mammoth\Math\Transform;
use Mammoth\Math\Vector;

use function Mammoth\Math\Vector;

// Shader sources
$vertexSource = <<<GLSL
    #version 150 core
    in vec2 position;
    in vec3 color;
    in vec2 texcoord;
    out vec3 Color;
    out vec2 Texcoord;
    uniform mat4 model;
    uniform mat4 view;
    uniform mat4 proj;
    void main()
    {
        Color = color;
        Texcoord = texcoord;
        gl_Position = proj * view * model * vec4(position, 0.0, 1.0);
    }
GLSL;

$fragmentSource = <<<GLSL
    #version 150 core
    in vec3 Color;
    in vec2 Texcoord;
    out vec4 outColor;
    uniform sampler2D texKitten;
    uniform sampler2D texPuppy;
    void main()
    {
        outColor = mix(texture(texKitten, Texcoord), texture(texPuppy, Texcoord), 0.5);
    }
GLSL;

    $t_start = microtime(true);

SDL_Init(SDL_INIT_EVERYTHING);

SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);

$window = SDL_CreateWindow("Shader animation", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);
SDL_GL_CreateContext($window);

// Create Vertex Array Object
glGenVertexArrays(1, $vaos);
$vao = $vaos[0];
glBindVertexArray($vao);

// Create a Vertex Buffer Object and copy the vertex data to it
glGenBuffers(1, $vbos);
$vbo = $vbos[0];

$vertices = [
//  Position      Color             Texcoords
    -0.5,  0.5, 1.0, 0.0, 0.0, 0.0, 0.0, // Top-left
     0.5,  0.5, 0.0, 1.0, 0.0, 1.0, 0.0, // Top-right
     0.5, -0.5, 0.0, 0.0, 1.0, 1.0, 1.0, // Bottom-right
    -0.5, -0.5, 1.0, 1.0, 1.0, 0.0, 1.0  // Bottom-left
];

glBindBuffer(GL_ARRAY_BUFFER, $vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof($vertices) * 4, $vertices, GL_STATIC_DRAW);

// Create an element array
glGenBuffers(1, $ebos);
$ebo = $ebos[0];

$elements = [
    0, 1, 2,
    2, 3, 0
];

glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, $ebo);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof($elements) * 4, $elements, GL_STATIC_DRAW);

// Create and compile the vertex shader
$vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource($vertexShader, 1, $vertexSource, NULL);
glCompileShader($vertexShader);

// Create and compile the fragment shader
$fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource($fragmentShader, 1, $fragmentSource, NULL);
glCompileShader($fragmentShader);

// Link the vertex and fragment shader into a shader program
$shaderProgram = glCreateProgram();
glAttachShader($shaderProgram, $vertexShader);
glAttachShader($shaderProgram, $fragmentShader);
glBindFragDataLocation($shaderProgram, 0, "outColor");
glLinkProgram($shaderProgram);
glUseProgram($shaderProgram);

// Specify the layout of the vertex data
$posAttrib = glGetAttribLocation($shaderProgram, "position");
glEnableVertexAttribArray($posAttrib);
glVertexAttribPointer($posAttrib, 2, GL_FLOAT, GL_FALSE, 7 * 4, 0);

$colAttrib = glGetAttribLocation($shaderProgram, "color");
glEnableVertexAttribArray($colAttrib);
glVertexAttribPointer($colAttrib, 3, GL_FLOAT, GL_FALSE, 7 * 4, (2 * 4));

$texAttrib = glGetAttribLocation($shaderProgram, "texcoord");
glEnableVertexAttribArray($texAttrib);
glVertexAttribPointer($texAttrib, 2, GL_FLOAT, GL_FALSE, 7 * 4, (5 * 4));

$imageLoader = new ImageLoader;

// Load textures
$textures = [];
glGenTextures(2, $textures);

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, $textures[0]);
$image = $imageLoader->load("textures/sample.png", $width, $height);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, $width, $height, 0, GL_RGBA, GL_UNSIGNED_BYTE, $image);
glUniform1i(glGetUniformLocation($shaderProgram, "texKitten"), 0);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, $textures[1]);
$image = $imageLoader->load("textures/sample2.png", $width, $height);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, $width, $height, 0, GL_RGBA, GL_UNSIGNED_BYTE, $image);
glUniform1i(glGetUniformLocation($shaderProgram, "texPuppy"), 1);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

$uniModel = glGetUniformLocation($shaderProgram, "model");

// Set up projection
$view = Transform::lookAt(
    new Vector(1.2, 1.2, 1.2),
    new Vector(0.0, 0.0, 0.0),
    new Vector(0.0, 0.0, 1.0)
);
$uniView = glGetUniformLocation($shaderProgram, "view");
glUniformMatrix4fv($uniView, 1, GL_FALSE, $view->toRowVector());

$proj = Transform::perspective((45.0), 800.0 / 600.0, 1.0, 10.0);
$uniProj = glGetUniformLocation($shaderProgram, "proj");
glUniformMatrix4fv($uniProj, 1, GL_FALSE, $proj->toRowVector());

$event = new SDL_Event;

while(true) {
    // Clear the screen to black
    glClearColor(0.1, 0.3, 0.3, 1.0);
    glClear(GL_COLOR_BUFFER_BIT);
    
    // Calculate transformation
    $t_now = microtime(true); 
    $time = $t_now - $t_start;
    
    $model = new Matrix();
    $model = Transform::rotate(
        $model,
        $time * Angle::toRadians(180.0),
        new Vector(0.0, 0.0, 1.0)
    );
    glUniformMatrix4fv($uniModel, 1, GL_FALSE, $model->toRowVector());

    // Draw a rectangle from the 2 triangles using 6 indices
    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, null);

    // Swap buffers
    SDL_GL_SwapWindow($window);

	SDL_PollEvent($event);
	if($event->type == SDL_KEYDOWN) break;
	
	SDL_Delay(20);
}

glDeleteTextures(2, $textures);

glDeleteProgram($shaderProgram);
glDeleteShader($fragmentShader);
glDeleteShader($vertexShader);

glDeleteBuffers(1, $ebo);
glDeleteBuffers(1, $vbo);

glDeleteVertexArrays(1, $vao);