/* * 3D Engine * triangle.c: * Based on pikuma.com 3D software renderer in C * Copyright (c) 2021 986-Studio. All rights reserved. * * Created by Manoƫl Trapier on 04/03/2021. */ #include #include #include <3dengine.h> #include #include #include vec3_t getTriangleNormal(vec4_t vertices[3]) { vec3_t ret; vec3_t vectorBA = vec3SubVectors(vec3FromVec4(vertices[1]), vec3FromVec4(vertices[0])); vec3_t vectorCA = vec3SubVectors(vec3FromVec4(vertices[2]), vec3FromVec4(vertices[0])); vec3Normalize(&vectorBA); vec3Normalize(&vectorCA); ret = vec3Cross(vectorBA, vectorCA); vec3Normalize(&ret); return ret; } void drawTriangle(int32_t x0, int32_t y0, int32_t x1, int32_t y1, int32_t x2, int32_t y2, colour_t colour) { drawLine(x0, y0, x1, y1, colour); drawLine(x1, y1, x2, y2, colour); drawLine(x2, y2, x0, y0, colour); } /* ----------------------------------- Filled triangles ----------------------------------- */ void drawFilledTriangle(struct triangle_t *t) { int32_t x, y; if (t->points[0].y > t->points[1].y) { doubleSwap(&t->points[0].x, &t->points[1].x); doubleSwap(&t->points[0].y, &t->points[1].y); doubleSwap(&t->points[0].z, &t->points[1].z); doubleSwap(&t->points[0].w, &t->points[1].w); } if (t->points[1].y > t->points[2].y) { doubleSwap(&t->points[1].x, &t->points[2].x); doubleSwap(&t->points[1].y, &t->points[2].y); doubleSwap(&t->points[1].z, &t->points[2].z); doubleSwap(&t->points[1].w, &t->points[2].w); } if (t->points[0].y > t->points[1].y) { doubleSwap(&t->points[0].x, &t->points[1].x); doubleSwap(&t->points[0].y, &t->points[1].y); doubleSwap(&t->points[0].z, &t->points[1].z); doubleSwap(&t->points[0].w, &t->points[1].w); } vec4_t a = t->points[0]; vec4_t b = t->points[1]; vec4_t c = t->points[2]; /* Render the top part */ double inverseSlope1 = 0; double inverseSlope2 = 0; int32_t x0 = a.x, y0 = a.y; int32_t x1 = b.x, y1 = b.y; int32_t x2 = c.x, y2 = c.y; if ((y1 - y0) != 0) { inverseSlope1 = (double)(x1 - x0) / abs(y1 - y0); } if ((y2 - y0) != 0) { inverseSlope2 = (double)(x2 - x0) / abs(y2 - y0); } if ((y1 - y0) != 0) { for (y = y0 ; y <= y1 ; y++) { int32_t xStart = x1 + (y - y1) * inverseSlope1; int32_t xEnd = x0 + (y - y0) * inverseSlope2; if (doZBuffer) { if (xEnd < xStart) { intSwap(&xStart, &xEnd); } for (x = xStart ; x <= xEnd ; x++) { drawZPixel(x, y, a, b, c,t->colour); } } else { drawHLine(xStart, y, xEnd, t->colour); } } } /* Render the bottom part */ inverseSlope1 = 0; if ((y2 - y1) != 0) { inverseSlope1 = (double)(x2 - x1) / abs(y2 - y1); } if ((y2 - y1) != 0) { for (y = y1 ; y <= y2 ; y++) { int32_t xStart = x2 + (y - y2) * inverseSlope1; int32_t xEnd = x0 + (y - y0) * inverseSlope2; if (doZBuffer) { if (xEnd < xStart) { intSwap(&xStart, &xEnd); } for (x = xStart ; x <= xEnd ; x++) { drawZPixel(x, y, a, b, c,t->colour); } } else { drawHLine(xStart, y, xEnd, t->colour); } } } } /* ----------------------------------- Textured triangles ----------------------------------- */ void drawTextureTriangle(struct triangle_t *t) { int32_t x, y; if (t->points[0].y > t->points[1].y) { doubleSwap(&t->points[0].x, &t->points[1].x); doubleSwap(&t->points[0].y, &t->points[1].y); doubleSwap(&t->points[0].z, &t->points[1].z); doubleSwap(&t->points[0].w, &t->points[1].w); doubleSwap(&t->textureCoordinates[0].u, &t->textureCoordinates[1].u); doubleSwap(&t->textureCoordinates[0].v, &t->textureCoordinates[1].v); } if (t->points[1].y > t->points[2].y) { doubleSwap(&t->points[1].x, &t->points[2].x); doubleSwap(&t->points[1].y, &t->points[2].y); doubleSwap(&t->points[1].z, &t->points[2].z); doubleSwap(&t->points[1].w, &t->points[2].w); doubleSwap(&t->textureCoordinates[1].u, &t->textureCoordinates[2].u); doubleSwap(&t->textureCoordinates[1].v, &t->textureCoordinates[2].v); } if (t->points[0].y > t->points[1].y) { doubleSwap(&t->points[0].x, &t->points[1].x); doubleSwap(&t->points[0].y, &t->points[1].y); doubleSwap(&t->points[0].z, &t->points[1].z); doubleSwap(&t->points[0].w, &t->points[1].w); doubleSwap(&t->textureCoordinates[0].u, &t->textureCoordinates[1].u); doubleSwap(&t->textureCoordinates[0].v, &t->textureCoordinates[1].v); } vec4_t a = t->points[0]; vec4_t b = t->points[1]; vec4_t c = t->points[2]; /* Render the top part */ double inverseSlope1 = 0; double inverseSlope2 = 0; int32_t x0 = a.x, y0 = a.y; int32_t x1 = b.x, y1 = b.y; int32_t x2 = c.x, y2 = c.y; if ((y1 - y0) != 0) { inverseSlope1 = (double)(x1 - x0) / abs(y1 - y0); } if ((y2 - y0) != 0) { inverseSlope2 = (double)(x2 - x0) / abs(y2 - y0); } if ((y1 - y0) != 0) { for (y = y0 ; y <= y1 ; y++) { int32_t xStart = x1 + (y - y1) * inverseSlope1; int32_t xEnd = x0 + (y - y0) * inverseSlope2; if (xEnd < xStart) { intSwap(&xStart, &xEnd); } for (x = xStart ; x <= xEnd ; x++) { drawTexel(x, y, a, b, c, t->textureCoordinates[0], t->textureCoordinates[1], t->textureCoordinates[2], t->texture); } } } /* Render the bottom part */ inverseSlope1 = 0; if ((y2 - y1) != 0) { inverseSlope1 = (double)(x2 - x1) / abs(y2 - y1); } if ((y2 - y1) != 0) { for (y = y1 ; y <= y2 ; y++) { int32_t xStart = x2 + (y - y2) * inverseSlope1; int32_t xEnd = x0 + (y - y0) * inverseSlope2; if (xEnd < xStart) { intSwap(&xStart, &xEnd); } for (x = xStart ; x <= xEnd ; x++) { drawTexel(x, y, a, b, c, t->textureCoordinates[0], t->textureCoordinates[1], t->textureCoordinates[2], t->texture); } } } } /* ---- Utility ---- */ int compareTrianglesZOrder(const void *p1, const void *p2) { triangle_t *t1 = (struct triangle_t *)p1; triangle_t *t2 = (struct triangle_t *)p2; if (t1->averageDepth > t2->averageDepth) { return -1; } else if (t1->averageDepth < t2->averageDepth) { return 1; } return 0; }