Use scanline algorithm for rasterization
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duarteapcoelho
parent
2d687fadf0
commit
59742c0343
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@ -79,90 +79,132 @@ namespace Rasterizer {
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};
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}
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struct Edge {
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int minY;
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int maxY;
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fp x;
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fp m;
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Edge *next;
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};
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Edge *newEdge(vec3i p0, vec3i p1){
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Edge *e = (Edge*) malloc(sizeof(Edge));
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if(p0.y > p1.y){
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*e = {
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p1.y,
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p0.y,
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p1.x,
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fp(p0.x - p1.x) / fp(p0.y - p1.y),
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nullptr
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};
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} else if(p0.y < p1.y){
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*e = {
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p0.y,
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p1.y,
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p0.x,
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fp(p1.x - p0.x) / fp(p1.y - p0.y),
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nullptr
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};
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} else {
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free(e);
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return nullptr;
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}
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return e;
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}
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void _drawTriangle(Triangle triangle, Shader shader, bool useDepth){
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vec3d p0_d = toDevice(triangle.p0);
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vec3d p1_d = toDevice(triangle.p1);
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vec3d p2_d = toDevice(triangle.p2);
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fp winding = cross({p1_d.x - p0_d.x, p1_d.y - p0_d.y, 0}, {p2_d.x - p0_d.x, p2_d.y - p0_d.y, 0});
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vec3i p0 = toScreen(p0_d);
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vec3i p1 = toScreen(p1_d);
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vec3i p2 = toScreen(p2_d);
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vec3i p0, p1, p2;
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if(winding > 0){
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p0 = toScreen(p0_d);
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p1 = toScreen(p1_d);
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p2 = toScreen(p2_d);
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} else {
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p0 = toScreen(p0_d);
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p1 = toScreen(p2_d);
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p2 = toScreen(p1_d);
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}
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int minX = max(min(min(p0.x, p1.x), p2.x), 0);
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int maxX = min(max(max(p0.x, p1.x), p2.x), RENDER_WIDTH);
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int minY = max(min(min(p0.y, p1.y), p2.y), 0);
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int maxY = min(max(max(p0.y, p1.y), p2.y), RENDER_HEIGHT);
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fp z = (p0.z + p1.z + p2.z) / 3;
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int e1 = edge({minX, minY, 0}, p0, p1);
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int e2 = edge({minX, minY, 0}, p1, p2);
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int e3 = edge({minX, minY, 0}, p2, p0);
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Edge *edgeTable[RENDER_HEIGHT];
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Edge *edges[3] = {
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newEdge(p0, p1),
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newEdge(p1, p2),
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newEdge(p2, p0),
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};
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fp bary_v, bary_w, bary_u;
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fp i_p0z, i_p1z, i_p2z;
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fp bary_v_per_x, bary_w_per_x, bary_u_per_x, bary_v_per_y, bary_w_per_y, bary_u_per_y;
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if(useDepth){
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const vec3i bary_v0 = {(p1.x - p0.x), (p1.y - p0.y), 0};
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const vec3i bary_v1 = {(p2.x - p0.x), (p2.y - p0.y), 0};
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fp bary_denom = (bary_v0.x * bary_v1.y - bary_v1.x * bary_v0.y);
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if(bary_denom == 0)
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return;
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const fp i_bary_denom = fp(1000) / fp(bary_v0.x * bary_v1.y - bary_v1.x * bary_v0.y);
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const vec3i bary_v2 = {minX - p0.x, minY - p0.y, 0};
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bary_v_per_x = fp(bary_v1.y) * fp(i_bary_denom) / fp(1000);
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bary_w_per_x = fp(0) - fp(bary_v0.y) * fp(i_bary_denom) / fp(1000);
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bary_u_per_x = fp(0) - bary_v_per_x - bary_w_per_x;
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bary_v_per_y = fp(0) - fp(bary_v1.x) * fp(i_bary_denom) / fp(1000);
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bary_w_per_y = fp(bary_v0.x) * fp(i_bary_denom) / fp(1000);
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bary_u_per_y = fp(0) -bary_v_per_y - bary_w_per_y;
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bary_v = fp(bary_v2.x * bary_v1.y - bary_v1.x * bary_v2.y) / fp(1000) * fp(i_bary_denom);
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bary_w = fp(bary_v0.x * bary_v2.y - bary_v2.x * bary_v0.y) / fp(1000) * fp(i_bary_denom);
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bary_u = fp(1) - bary_v - bary_w;
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i_p0z = fp(1)/fp(p0.z);
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i_p1z = fp(1)/fp(p1.z);
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i_p2z = fp(1)/fp(p2.z);
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for(int y = 0; y < RENDER_HEIGHT; y++){
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edgeTable[y] = nullptr;
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for(int i = 0; i < 3; i++){
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if(edges[i] != nullptr){
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if(edges[i]->minY == y){
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Edge **e = &(edgeTable[y]);
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while(*e != nullptr){
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e = &((*e)->next);
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}
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*e = edges[i];
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}
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}
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}
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}
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Edge *activeEdgeList = nullptr;
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for(int y = minY; y < maxY; y++){
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// bool hasEntered = false;
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int ie1 = e1;
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int ie2 = e2;
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int ie3 = e3;
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// add new edges to the list
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if(edgeTable[y] != nullptr){
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Edge **e;
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for(e = &activeEdgeList; *e != nullptr; e = &((*e)->next)){
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}
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*e = edgeTable[y];
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}
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fp i_bary_v = bary_v;
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fp i_bary_w = bary_w;
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fp i_bary_u = bary_u;
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// remove edges from the list
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for(Edge **e = &activeEdgeList; *e != nullptr;){
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if(y == (*e)->maxY){
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*e = (*e)->next;
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} else {
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e = &((*e)->next);
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}
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}
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for(int x = minX; x < maxX; x++){
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if(ie1 >= 0 && ie2 >= 0 && ie3 >= 0) {
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bool visible = true;
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fp i_z;
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if(useDepth){
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vec3d b = {i_bary_u, i_bary_v, i_bary_w};
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// i_z = (b.x * i_p0z + b.y * i_p1z + b.z * i_p2z);
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i_z.i = ((b.x.i * i_p0z.i) + (b.y.i * i_p1z.i) + (b.z.i * i_p2z.i));
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if(i_z > depthBuffer[x+y*RENDER_WIDTH] || depthBuffer[x+y*RENDER_WIDTH] == -1){
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depthBuffer[x+y*RENDER_WIDTH] = i_z;
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#if PIXEL_SIZE == 1
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Display::drawPoint(x, y, triangle.c);
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#else
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Display::fillRect(x*PIXEL_SIZE, y*PIXEL_SIZE, PIXEL_SIZE, PIXEL_SIZE, triangle.c);
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#endif
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}
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} else {
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// calculate intersection point
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for(Edge *e = activeEdgeList; e != nullptr; e = e->next){
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e->x = e->x + e->m;
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}
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// sort by intersection point using injection sort:
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Edge *sortedEdgeList = nullptr;
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// sort
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for(Edge *e = activeEdgeList; e != nullptr;){
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Edge *next = e->next;
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for(Edge **f = &sortedEdgeList;; f = &((*f)->next)){
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if(*f == nullptr){
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*f = e;
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(*f)->next = nullptr;
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break;
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}
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if((*f)->x > e->x){
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Edge *a = *f;
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*f = e;
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e->next = a;
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break;
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}
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}
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e = next;
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}
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activeEdgeList = sortedEdgeList;
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// draw
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for(Edge *e = activeEdgeList; e != nullptr; e = e->next->next){
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int minX = min(max(e->x, 0), RENDER_WIDTH);
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int maxX = max(min(e->next->x, RENDER_WIDTH), 0);
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for(int x = minX; x < maxX; x++){
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if(z < depthBuffer[x+y*RENDER_WIDTH] || depthBuffer[x+y*RENDER_WIDTH] == -1 || !useDepth){
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if(useDepth)
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depthBuffer[x+y*RENDER_WIDTH] = z;
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#if PIXEL_SIZE == 1
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Display::drawPoint(x, y, triangle.c);
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#else
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@ -170,26 +212,18 @@ namespace Rasterizer {
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#endif
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}
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}
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ie1 += (p0.y - p1.y);
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ie2 += (p1.y - p2.y);
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ie3 += (p2.y - p0.y);
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if(useDepth){
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i_bary_v = i_bary_v + bary_v_per_x;
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i_bary_w = i_bary_w + bary_w_per_x;
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i_bary_u = i_bary_u + bary_u_per_x;
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}
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// if(z < depthBuffer[y] || depthBuffer[y] == -1 || !useDepth){
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// if(useDepth)
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// depthBuffer[y] = z;
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// Display::fillRect(minX * PIXEL_SIZE, y*PIXEL_SIZE, (maxX - minX) * PIXEL_SIZE, PIXEL_SIZE, triangle.c);
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// }
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}
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e1 -= (p0.x - p1.x);
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e2 -= (p1.x - p2.x);
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e3 -= (p2.x - p0.x);
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}
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if(useDepth){
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bary_v = bary_v + bary_v_per_y;
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bary_w = bary_w + bary_w_per_y;
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bary_u = bary_u + bary_u_per_y;
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for(int i = 0; i < 3; i++){
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if(edges[i] != nullptr){
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free(edges[i]);
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}
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}
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}
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