trimill.xyz/flaskr/templates/projects/complex_grapher/webgl_base.js

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JavaScript
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2022-06-23 05:58:54 +00:00
const vsSource = `#version 300 es
in vec4 aVertexPosition;
void main() {
gl_Position = aVertexPosition;
}
`;
function runShader(fsSource, options) {
const canvas = document.querySelector('#canvas');
const gl = canvas.getContext('webgl2', {preserveDrawingBuffer:true});
if (!gl) {
alert('could not initialize webgl.');
return;
}
const shaderProgram = initShaderProgram(gl, vsSource, fsSource);
gl.useProgram(shaderProgram);
const vertexPosition = gl.getAttribLocation(shaderProgram, 'aVertexPosition');
uResolution = gl.getUniformLocation(shaderProgram, "uResolution");
uRangeAxes = gl.getUniformLocation(shaderProgram, "uRangeAxes");
uDrawContours = gl.getUniformLocation(shaderProgram, "uDrawContours");
uShadingIntensity = gl.getUniformLocation(shaderProgram, "uShadingIntensity");
uSwapBlackWhite = gl.getUniformLocation(shaderProgram, "uSwapBlackWhite");
uIterations = gl.getUniformLocation(shaderProgram, "uIterations");
uSmoothColor = gl.getUniformLocation(shaderProgram, "uSmoothColor");
gl.uniform2f(uResolution, gl.canvas.width, gl.canvas.height);
gl.uniform4f(uRangeAxes, options.rmin, options.rmax, options.imin, options.imax);
gl.uniform1i(uDrawContours, options.drawcontours ? 1 : 0);
gl.uniform1f(uShadingIntensity, options.shading);
gl.uniform1i(uSwapBlackWhite, options.swapbw) ? 1 : 0;
gl.uniform1i(uIterations, options.iterations);
gl.uniform1i(uSmoothColor, options.smoothcolor);
const buffers = initBuffers(gl);
drawScene(gl, vertexPosition, buffers);
}
function initBuffers(gl) {
const positionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
const positions = [
1.0, 1.0,
-1.0, 1.0,
1.0, -1.0,
-1.0, -1.0,
];
gl.bufferData(gl.ARRAY_BUFFER,
new Float32Array(positions),
gl.STATIC_DRAW);
return {
position: positionBuffer,
};
}
function drawScene(gl, vertexPosition, buffers) {
gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.clearDepth(1.0);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
const projectionMatrix = mat4.create();
const modelViewMatrix = mat4.create();
const numComponents = 2;
const type = gl.FLOAT;
const normalize = false;
const stride = 0;
const offset = 0;
gl.bindBuffer(gl.ARRAY_BUFFER, buffers.position);
gl.vertexAttribPointer(
vertexPosition,
numComponents,
type,
normalize,
stride,
offset);
gl.enableVertexAttribArray(vertexPosition);
const vertexOffset = 0;
const vertexCount = 4;
gl.drawArrays(gl.TRIANGLE_STRIP, vertexOffset, vertexCount);
}
function initShaderProgram(gl, vsSource, fsSource) {
const vertexShader = loadShader(gl, gl.VERTEX_SHADER, vsSource);
const fragmentShader = loadShader(gl, gl.FRAGMENT_SHADER, fsSource);
const shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
throw Error('could not initialize shader program: ' + gl.getProgramInfoLog(shaderProgram));
}
gl.deleteShader(vertexShader);
gl.deleteShader(fragmentShader);
return shaderProgram;
}
function loadShader(gl, type, source) {
const shader = gl.createShader(type);
gl.shaderSource(shader, source);
gl.compileShader(shader);
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
const text = 'could not compile shaders: ' + gl.getShaderInfoLog(shader);
gl.deleteShader(shader);
throw Error(text);
}
return shader;
}