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Draw the cylinder instead of the square

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The textures are broken because I misunderstood that the texture
coordinates must correlate with vertices, not elements.
This commit is contained in:
Brandon Dyck 2022-10-23 15:43:13 -06:00
parent 270de0a9b1
commit 8f59344b7d
1 changed files with 43 additions and 36 deletions
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79
panorama-viewer.js
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@ -10,7 +10,7 @@
// The number of parallels, including the poles, dividing the sphere's surface.
// Two parallels would make a vertical line segment.
if (parallels < 3) {
throw "parallels must be ≥ 3";
// throw "parallels must be ≥ 3";
}
const radius = 1;
@ -18,8 +18,8 @@
const positions = new Float32Array(meridians * parallels * 3);
let positionsIdx = 0;
for (let p = 0; p < parallels; p++) {
const y = -radius + p * 2 * radius / parallels;
for (let m = 0; m < meridians; m++) {
const y = p * 2 * radius / (parallels - 1) - radius;
for (let m = 0; m <= meridians; m++) {
const θ = m * 2 * Math.PI / meridians;
const x = Math.sin(θ) * radius;
const z = Math.cos(θ) * radius;
@ -58,14 +58,14 @@
const currTextureCoords = [
// Lower triangle
m / meridians, p / parallels,
(m + 1) / meridians, p / parallels,
(m + 1) / meridians, (p + 1) / parallels,
m / meridians, p / (parallels - 1),
(m + 1) / meridians, p / (parallels - 1),
(m + 1) / meridians, (p + 1) / (parallels - 1),
// Upper triangle
m / meridians, p / parallels,
(m + 1) / meridians, (p + 1) / parallels,
m / meridians, (p + 1) / parallels,
m / meridians, p / (parallels - 1),
(m + 1) / meridians, (p + 1) / (parallels - 1),
m / meridians, (p + 1) / (parallels - 1),
];
for (const coord of currTextureCoords) {
textureCoords[textureCoordsIdx++] = coord;
@ -73,9 +73,13 @@
}
}
return { positions, textureCoords, indices };
return {
positions, textureCoords, indices,
positionStride: 3 * positions.constructor.BYTES_PER_ELEMENT,
textureCoordStride: 2 * textureCoords.constructor.BYTES_PER_ELEMENT,
};
}
console.log(makeCylinder());
// console.log(makeCylinder());
const initShaderProgram = (gl) => {
const vShaderSrc = `
@ -97,7 +101,12 @@
uniform sampler2D sampler;
void main() {
gl_FragColor = texture2D(sampler, vTextureCoord);
if (gl_FrontFacing) {
gl_FragColor = texture2D(sampler, vTextureCoord);
} else {
gl_FragColor = vec4(0.5,0,0,1);
}
}
`;
@ -138,18 +147,19 @@
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
});
return texture;
};
let viewer = document.getElementById("viewer");
let gl = viewer.getContext("webgl2");
let gl = viewer.getContext("webgl");
let program = initShaderProgram(gl);
let modelMatrixLocation = gl.getUniformLocation(program, "modelMatrix");
// Set up mouse-panning state machine.
let θy = 0;
let θx = 0.25;
let θx = 0;
const PanState = Object.freeze({
idle: (event) => {
if (event.type === "mousedown") {
@ -184,29 +194,24 @@
viewer.addEventListener("mousemove", runPanState);
gl.useProgram(program);
let vertexBuffer = gl.createBuffer();
let vertices = new Float32Array([
// x, y, z, u, v
0, 0, 0, 0, 0,
1, 0, 0, 1, 0,
1, 1, 0, 1, 1,
0, 1, 0, 0, 1,
]);
const vertexStride = 4 * 5;
const positionOffset = 0;
const textureCoordOffset = 4 * 3;
gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW);
const cylinder = makeCylinder(3, 3);
console.log(cylinder);
let positionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
gl.bufferData(gl.ARRAY_BUFFER, cylinder.positions, gl.STATIC_DRAW);
const positionLocation = gl.getAttribLocation(program, "position");
let textureCoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, textureCoordBuffer);
gl.bufferData(gl.ARRAY_BUFFER, cylinder.textureCoords, gl.STATIC_DRAW);
const textureCoordLocation = gl.getAttribLocation(program, "textureCoord");
let indexBuffer = gl.createBuffer();
let indices = new Uint16Array([
0, 1, 2,
3, 0, 2,
]);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, indices, gl.STATIC_DRAW);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, cylinder.indices, gl.STATIC_DRAW);
gl.enable(gl.CULL_FACE);
// Load texture
let image = document.getElementById("image");
@ -222,14 +227,16 @@
mat4.rotateY(modelMatrix, modelMatrix, θy);
gl.uniformMatrix4fv(modelMatrixLocation, false, modelMatrix);
gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
gl.enableVertexAttribArray(positionLocation);
gl.vertexAttribPointer(positionLocation, 3, gl.FLOAT, false, vertexStride, positionOffset);
gl.drawElements(gl.TRIANGLES, indices.length, gl.UNSIGNED_SHORT, 0);
gl.vertexAttribPointer(positionLocation, 3, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, textureCoordBuffer);
gl.enableVertexAttribArray(textureCoordLocation);
gl.vertexAttribPointer(textureCoordLocation, 2, gl.FLOAT, false, vertexStride, textureCoordOffset);
gl.vertexAttribPointer(textureCoordLocation, 2, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
gl.drawElements(gl.TRIANGLES, 12, gl.UNSIGNED_SHORT, 0);
requestAnimationFrame(render);
};