+init

1 files changed, 180 insertions, 0 deletions

diff --git a/src/core/rasterizer.c b/src/core/rasterizer.c
new file mode 100644
index 0000000..0c8c6eb
--- /dev/null
+++ b/src/core/rasterizer.c
@@ -0,0 +1,180 @@
+#include "rasterizer.h"
+#include "device.h"
+#include "shader.h"
+#include "../math/math.h"
+#include "../util/assert.h"
+
+void ssrR_putline(int x0, int y0, int x1, int y1, Color color) {
+	int steep = 0;
+	if (abs(x0 - x1) < abs(y0 - y1)) {
+		swapi(x0, y0);
+		swapi(x1, y1);
+		steep = 1;
+	}
+	if (x0 > x1) {
+		swapi(x0, x1);
+		swapi(y0, y1);
+	}
+	int dx = x1 - x0;
+	int dy = y1 - y0;
+	int derror2 = abs(dy) << 1;
+	int error2 = 0;
+	int y = y0;
+	for (int x = x0; x <= x1; ++x) {
+		if (steep) {
+			ssr_putpoint(y, x, color);
+		}
+		else {
+			ssr_putpoint(x, y, color);
+		}
+		error2 += derror2;
+		if (error2 > dx) {
+			y += (y1 > y0 ? 1 : -1);
+			error2 -= (dx << 1);
+		}
+	}
+}
+
+/*使用辅助梯形计算三角形面积，《3D数学基础》P245*/
+float ssrR_area(Vec2* v1, Vec2* v2, Vec2* v3) {
+	ssr_assert(v1 && v2 && v3);
+	float area  = 0.5f * ((v1->y - v2->y) * (v3->x - v2->x) + (v3->y - v2->y) * (v2->x - v1->x));
+	return area;
+}
+
+/*from https://github.com/ssloy/tinyrenderer*/
+static Vec3 s[2], u;
+bool ssrR_barycentric(Vec2* A, Vec2* B, Vec2* C, Vec2* p, Vec3* out) {
+	ssr_assert(A && B && C && p && out);
+	s[0].x = C->x - A->x; s[0].y = B->x - A->x; s[0].z = A->x - p->x;
+	s[1].x = C->y - A->y; s[1].y = B->y - A->y; s[1].z = A->y - p->y;
+	vec3_cross(&s[0], &s[1], &u);
+	if (compare(u.z, 0)) {
+		return 0;
+	} else {
+		float uz = 1.f / u.z;
+		out->x = 1 - (u.x + u.y) * uz;
+		out->y = u.y * uz;
+		out->z = u.x * uz;
+		return 1;
+	}
+}
+
+bool ssrR_ispointintriangle(Vec2* A, Vec2* B, Vec2* C, Vec2* p) {
+	ssr_assert(A && B && C && p);
+	Vec3 c; ssrR_barycentric(A, B, C, p, &c);
+	return c.x >= 0 && c.y >= 0 && c.z >= 0;
+}
+
+void ssrR_center(Vec2* A, Vec2* B, Vec2* C, Vec2* out) {
+	ssr_assert(A && B && C && out);
+	float k = 1 / 3.f;
+	out->x = k * (A->x + B->x + C->x);
+	out->y = k * (A->y + B->y + C->y);
+}
+
+/*
+** clipc 按列排放的三角形三个顶点的齐次裁剪坐标
+** program shader程序
+*/
+static Vec3 SA, SB, SC; // screen coords
+static Vec3 bcp; // 重心坐标
+void _ssrR_triangle(Vec4* CA, Vec4* CB, Vec4* CC, Vert* A, Vert* B, Vert* C, Program* program, UniformCollection* uniforms) {
+	ssr_assert(CA && CB && CC && program);
+	vec4_dividew(CA, &SA); ssrU_viewport(&SA, &SA);
+	vec4_dividew(CB, &SB); ssrU_viewport(&SB, &SB);
+	vec4_dividew(CC, &SC); ssrU_viewport(&SC, &SC);
+	/*根据屏幕空间的y值排序, A的y最小，B居中，C最大*/
+	Vec3 *sa = &SA, *sb = &SB, *sc = &SC, *tmp; Vec4* v4tmp; Vert* vtemp;
+	if (sb->y < sa->y) { sa = &SB; sb = &SA; v4tmp = CA; CA = CB; CB = v4tmp; vtemp = A; A = B; B = vtemp; }
+	if (sc->y < sb->y) { tmp = sc; sc = sb; sb = tmp; v4tmp = CC; CC = CB; CB = v4tmp; vtemp = B; B = C; C = vtemp; }
+	if (sc->y < sa->y) { tmp = sc; sc = sa; sa = tmp; v4tmp = CC; CC = CA; CA = v4tmp; vtemp = C; C = A; A = vtemp; }
+
+	float invkAC = (SC.x - SA.x) / (SC.y - SA.y + EPSILON);
+	float invkAB = (SB.x - SA.x) / (SB.y - SA.y + EPSILON);
+	float invkBC = (SC.x - SB.x) / (SC.y - SB.y + EPSILON);
+
+	int order = 1; if (((sb->y - sa->y) / (sb->x - sa->x) - invkAC) * invkAC > 0) { order = -1; }
+
+	FragmentShaderIn in = {A, B, C, 0};
+	Color color;
+	Vec2 l, r, p;
+	float depth; Vec3 cdepth = {SA.z, SB.z, SC.z};
+	float CAw = 1.f / CA->w, CBw = 1.f / CB->w, CCw = 1.f / CC->w;
+	for (p.y = sa->y; p.y <= sc->y; ++p.y) {
+		l.y = p.y; 
+		r.y = p.y;
+		if (compare(SC.y, SA.y)) r.x = sc->x;
+		else r.x = sa->x + invkAC * (p.y - sa->y); /*AC*/
+		if (p.y <= sb->y) {
+			if (compare(SB.y, SA.y)) l.x = sb->x;
+			else l.x = sa->x + invkAB * (p.y - sa->y);
+		} else {
+			if (compare(SC.y, SB.y)) l.x = sc->x;
+			else l.x = sb->x + invkBC * (p.y - sb->y);
+		}
+		for (p.x = l.x; order * (r.x - p.x) >= 0; p.x += order) {
+			/*计算线性的（齐次裁剪空间）的重心坐标，分三步*/
+			if (!ssrR_barycentric(sa, sb, sc, &p, &bcp)) {
+				continue; /*discard fragment*/
+			}
+			bcp.x *= CAw; bcp.y *= CBw; bcp.z *= CCw;
+			vec3_scale(&bcp, 1.f / (bcp.x + bcp.y + bcp.z), &bcp);
+			/*depth test*/
+			depth = vec3_dot(&bcp, &cdepth) * 0.5f + 0.5f;
+			if (!ssr_testdepthf(p.x, p.y, depth)) {
+				continue; /*discard fragment*/
+			}
+			/*enter fragment shader*/
+			in.bc = &bcp;
+			program->fragmentshader(uniforms, &in, &color);
+			ssr_putpoint(p.x, p.y, color);
+		}
+	}
+}
+
+static Vec2 bboxmin, bboxmax;
+void ssrR_triangle(Vec4* CA, Vec4* CB, Vec4* CC, Vert* A, Vert* B, Vert* C, Program* program, UniformCollection* uniforms) {
+	ssr_assert(CA && CB && CC && program);
+	vec4_dividew(CA, &SA); ssrU_viewport(&SA, &SA);
+	vec4_dividew(CB, &SB); ssrU_viewport(&SB, &SB);
+	vec4_dividew(CC, &SC); ssrU_viewport(&SC, &SC);
+	bboxmin.x = min(SA.x, min(SB.x, SC.x));
+	bboxmax.x = max(SA.x, max(SB.x, SC.x));
+	bboxmin.y = min(SA.y, min(SB.y, SC.y));
+	bboxmax.y = max(SA.y, max(SB.y, SC.y));
+	float CAw = 1.f / CA->w, CBw = 1.f / CB->w, CCw = 1.f / CC->w;
+	float depth; Vec3 cdepth = { SA.z, SB.z, SC.z };
+	FragmentShaderIn in = { A, B, C, 0 };
+	Vec2 p;	Color color;
+	for (p.y = bboxmin.y; p.y <= bboxmax.y; ++p.y) {
+		for (p.x = bboxmin.x; p.x <= bboxmax.x; ++p.x) {
+			/*计算线性的（齐次裁剪空间）的重心坐标，分三步*/
+			if (!ssrR_barycentric(&SA, &SB, &SC, &p, &bcp)) {
+				continue; /*discard fragment*/
+			}
+			if (bcp.x < 0 || bcp.y < 0 || bcp.z < 0) {
+				continue; /*discard fragment*/
+			}
+			bcp.x *= CAw; bcp.y *= CBw; bcp.z *= CCw;
+			vec3_scale(&bcp, 1.f / (bcp.x + bcp.y + bcp.z), &bcp);
+
+			/*深度测试*/
+			if (ssr_isenable(ENABLEMASK_DEPTHTEST)) {
+				depth = vec3_dot(&bcp, &cdepth) * 0.5f + 0.5f;
+				if (!ssr_testdepthf(p.x, p.y, depth)) {
+					continue; /*discard fragment*/
+				}
+			}
+
+			/*enter fragment shader*/
+			in.bc = &bcp;
+			bool discad = program->fragmentshader(uniforms, &in, &color);
+			if (!discad)
+				ssr_putpoint(p.x, p.y, color);
+		}
+	}
+	//ssrR_putline(SA.x, SA.y, SB.x, SB.y, 0xffff0000);
+	//ssrR_putline(SA.x, SA.y, SC.x, SC.y, 0xffff0000);
+	//ssrR_putline(SC.x, SC.y, SB.x, SB.y, 0xffff0000);
+}
\ No newline at end of file