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Path: blob/master/GPU/Software/trirast.txt
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function drawPixel( x, y, r, g, b ) {12var offset = ( x + y * canvasWidth ) * 4;34if ( data[ offset + 3 ] ) return;56data[ offset ] = r;7data[ offset + 1 ] = g;8data[ offset + 2 ] = b;9data[ offset + 3 ] = 255;1011}1213function clearRectangle( x1, y1, x2, y2 ) {1415var xmin = Math.max( Math.min( x1, x2 ), 0 );16var xmax = Math.min( Math.max( x1, x2 ), canvasWidth );17var ymin = Math.max( Math.min( y1, y2 ), 0 );18var ymax = Math.min( Math.max( y1, y2 ), canvasHeight );1920var offset = ( xmin + ymin * canvasWidth - 1 ) * 4 + 3;21var linestep = ( canvasWidth - ( xmax - xmin ) ) * 4;2223for ( var y = ymin; y < ymax; y ++ ) {2425for ( var x = xmin; x < xmax; x ++ ) {2627data[ offset += 4 ] = 0;2829}3031offset += linestep;3233}3435}3637function drawTriangle( x1, y1, x2, y2, x3, y3, r, g, b ) {3839// https://gist.github.com/248610140// explanation: ttp://pouet.net/topic.php?which=8760&page=14142// 28.4 fixed-point coordinates4344var x1 = Math.round( 16 * x1 );45var x2 = Math.round( 16 * x2 );46var x3 = Math.round( 16 * x3 );4748var y1 = Math.round( 16 * y1 );49var y2 = Math.round( 16 * y2 );50var y3 = Math.round( 16 * y3 );5152// Deltas5354var dx12 = x1 - x2, dy12 = y2 - y1;55var dx23 = x2 - x3, dy23 = y3 - y2;56var dx31 = x3 - x1, dy31 = y1 - y3;5758// Bounding rectangle5960var minx = Math.max( ( Math.min( x1, x2, x3 ) + 0xf ) >> 4, 0 );61var maxx = Math.min( ( Math.max( x1, x2, x3 ) + 0xf ) >> 4, canvasWidth );62var miny = Math.max( ( Math.min( y1, y2, y3 ) + 0xf ) >> 4, 0 );63var maxy = Math.min( ( Math.max( y1, y2, y3 ) + 0xf ) >> 4, canvasHeight );6465rectx1 = Math.min( minx, rectx1 );66rectx2 = Math.max( maxx, rectx2 );67recty1 = Math.min( miny, recty1 );68recty2 = Math.max( maxy, recty2 );6970// Block size, standard 8x8 (must be power of two)7172var q = blocksize;7374// Start in corner of 8x8 block7576minx &= ~(q - 1);77miny &= ~(q - 1);7879// Constant part of half-edge functions8081var c1 = dy12 * ((minx << 4) - x1) + dx12 * ((miny << 4) - y1);82var c2 = dy23 * ((minx << 4) - x2) + dx23 * ((miny << 4) - y2);83var c3 = dy31 * ((minx << 4) - x3) + dx31 * ((miny << 4) - y3);8485// Correct for fill convention8687if ( dy12 > 0 || ( dy12 == 0 && dx12 > 0 ) ) c1 ++;88if ( dy23 > 0 || ( dy23 == 0 && dx23 > 0 ) ) c2 ++;89if ( dy31 > 0 || ( dy31 == 0 && dx31 > 0 ) ) c3 ++;9091// Note this doesn't kill subpixel precision, but only because we test for >=0 (not >0).92// It's a bit subtle. :)93c1 = (c1 - 1) >> 4;94c2 = (c2 - 1) >> 4;95c3 = (c3 - 1) >> 4;9697// Set up min/max corners98var qm1 = q - 1; // for convenience99var nmin1 = 0, nmax1 = 0;100var nmin2 = 0, nmax2 = 0;101var nmin3 = 0, nmax3 = 0;102if (dx12 >= 0) nmax1 -= qm1*dx12; else nmin1 -= qm1*dx12;103if (dy12 >= 0) nmax1 -= qm1*dy12; else nmin1 -= qm1*dy12;104if (dx23 >= 0) nmax2 -= qm1*dx23; else nmin2 -= qm1*dx23;105if (dy23 >= 0) nmax2 -= qm1*dy23; else nmin2 -= qm1*dy23;106if (dx31 >= 0) nmax3 -= qm1*dx31; else nmin3 -= qm1*dx31;107if (dy31 >= 0) nmax3 -= qm1*dy31; else nmin3 -= qm1*dy31;108109// Loop through blocks110var linestep = (canvasWidth - q) * 4;111var scale = 255.0 / (c1 + c2 + c3);112113var cb1 = c1;114var cb2 = c2;115var cb3 = c3;116var qstep = -q;117var e1x = qstep * dy12;118var e2x = qstep * dy23;119var e3x = qstep * dy31;120var x0 = minx;121122for (var y0 = miny; y0 < maxy; y0 += q) {123124// New block line - keep hunting for tri outer edge in old block line dir125while (x0 >= minx && x0 < maxx && cb1 >= nmax1 && cb2 >= nmax2 && cb3 >= nmax3) {126127x0 += qstep;128cb1 += e1x;129cb2 += e2x;130cb3 += e3x;131132}133134// Okay, we're now in a block we know is outside. Reverse direction and go into main loop.135qstep = -qstep;136e1x = -e1x;137e2x = -e2x;138e3x = -e3x;139140while (1) {141142// Step everything143x0 += qstep;144cb1 += e1x;145cb2 += e2x;146cb3 += e3x;147148// We're done with this block line when at least one edge completely out149// If an edge function is too small and decreasing in the current traversal150// dir, we're done with this line.151if (x0 < minx || x0 >= maxx) break;152if (cb1 < nmax1) if (e1x < 0) break; else continue;153if (cb2 < nmax2) if (e2x < 0) break; else continue;154if (cb3 < nmax3) if (e3x < 0) break; else continue;155156// We can skip this block if it's already fully covered157var blockX = (x0 / q) | 0;158var blockY = (y0 / q) | 0;159var blockInd = blockX + blockY * canvasWBlocks;160if (block_full[blockInd]) continue;161162// Offset at top-left corner163var offset = (x0 + y0 * canvasWidth) * 4;164165// Accept whole block when fully covered166if (cb1 >= nmin1 && cb2 >= nmin2 && cb3 >= nmin3) {167168var cy1 = cb1;169var cy2 = cb2;170171for ( var iy = 0; iy < q; iy ++ ) {172173var cx1 = cy1;174var cx2 = cy2;175176for ( var ix = 0; ix < q; ix ++ ) {177178if (!data[offset + 3]) {179180var u = cx1 * scale; // 0-255!181var v = cx2 * scale; // 0-255!182data[offset] = u;183data[offset + 1] = v;184data[offset + 2] = 0;185data[offset + 3] = 255;186187}188189cx1 += dy12;190cx2 += dy23;191offset += 4;192193}194195cy1 += dx12;196cy2 += dx23;197offset += linestep;198199}200201block_full[blockInd] = 1;202203} else { // Partially covered block204205var cy1 = cb1;206var cy2 = cb2;207var cy3 = cb3;208209for ( var iy = 0; iy < q; iy ++ ) {210211var cx1 = cy1;212var cx2 = cy2;213var cx3 = cy3;214215for ( var ix = 0; ix < q; ix ++ ) {216217if ( (cx1 | cx2 | cx3) >= 0 && !data[offset+3]) {218219var u = cx1 * scale; // 0-255!220var v = cx2 * scale; // 0-255!221data[offset] = u;222data[offset + 1] = v;223data[offset + 2] = 0;224data[offset + 3] = 255;225226}227228cx1 += dy12;229cx2 += dy23;230cx3 += dy31;231offset += 4;232233}234235cy1 += dx12;236cy2 += dx23;237cy3 += dx31;238offset += linestep;239240}241242}243244}245246// Advance to next row of blocks247cb1 += q*dx12;248cb2 += q*dx23;249cb3 += q*dx31;250251}252253}254255function normalToComponent( normal ) {256257var component = ( normal + 1 ) * 127;258return component < 0 ? 0 : ( component > 255 ? 255 : component );259260}261262};263264