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#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);
}
static void puttriangle(Vec2* A, Vec2* B, Vec2* C, Color c) {
ssr_assert(A && B && C);
ssrR_putline(A->x, A->y, B->x, B->y, c);
ssrR_putline(A->x, A->y, C->x, C->y, c);
ssrR_putline(C->x, C->y, B->x, B->y, c);
}
extern FragmentShaderIn ssr_frag_in;
void ssrR_triangle(
Vec4* CA, Vec4* CB, Vec4* CC,
uint IA, uint IB, uint IC,
Program* program,
UniformCollection* uniforms
) {
ssr_assert(CA && CB && CC && program);
Vec3 SA, SB, SC;
vec4_dividew(CA, &SA); ssrU_viewport(&SA, &SA);
vec4_dividew(CB, &SB); ssrU_viewport(&SB, &SB);
vec4_dividew(CC, &SC); ssrU_viewport(&SC, &SC);
/*
puttriangle(&SA, &SB, &SC, 0xffff0000);
return;
*/
Vec3 *sa = &SA, *sb = &SB, *sc = &SC, *tmp;
Vec4 *v4tmp;
uint itmp;
#define swap(t, a, b) {t = a; a = b; b = t;} /*sort in y axis*/
if (sb->y < sa->y) { swap(tmp, sa, sb); swap(v4tmp, CA, CB); swap(itmp, IA, IB); }
if (sc->y < sb->y) { swap(tmp, sb, sc); swap(v4tmp, CB, CC); swap(itmp, IB, IC); }
if (sb->y < sa->y) { swap(tmp, sa, sb); swap(v4tmp, CA, CB); swap(itmp, IA, IB); }
#undef swap
Vec2 AB = {sb->x - sa->x, sb->y - sa->y}, AC = { sc->x - sa->x, sc->y - sa->y };
int order = (AB.x * AC.y - AC.x * AB.y) > 0 ? 1 : -1;
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);
float from, to;
float depth;
float CAw = 1.f / CA->w, CBw = 1.f / CB->w, CCw = 1.f / CC->w;
bool depth_test = ssr_isenable(ENABLE_DEPTHTEST);
bool multi_sample = ssr_isenable(ENABLE_MULTISAMPLE);
bool blend = ssr_isenable(ENABLE_BLEND);
bool write_depth = ssr_isenable(ENABLE_WRITEDEPTH);
bool stencil_test = ssr_isenable(ENABLE_STENCILTEST);
bool write_stencil = ssr_iswritesencil();
bool pass_depth_test = TRUE;
bool pass_stencil_test = TRUE;
bool discard = FALSE;
FragmentShader frag_shader = program->fragmentshader;
Vec3 s[2], u; /*edge of triangle*/
s[0].x = sc->x - sa->x; s[0].y = sb->x - sa->x;
s[1].x = sc->y - sa->y; s[1].y = sb->y - sa->y;
Vec2 p;
Vec3 bc;
#define discardif(condition) if(condition) continue
#define RENDER_TRIANGLE \
for (p.y = FROM->y; p.y < TO->y + OFFSET; ++p.y) { \
SET_FROM_AND_TO \
s[1].z = sa->y - p.y; \
for (p.x = from; order * (p.x - to) <= 0; p.x += order) { \
/*calculate barycentric coordinate*/ \
s[0].z = sa->x - p.x; \
vec3_cross(&s[0], &s[1], &u); \
discardif(compare(u.z, 0)); \
u.z = 1.f / u.z; \
bc.x = 1.f - (u.x + u.y) * u.z; \
bc.y = u.y * u.z; \
bc.z = u.x * u.z; \
discardif(bc.x < 0 || bc.y < 0 || bc.z < 0); \
/*perspective correction*/ \
bc.x *= CAw; bc.y *= CBw; bc.z *= CCw; \
vec3_scale(&bc, 1.f / (bc.x + bc.y + bc.z), &bc); \
/*early depth testing*/ \
if(depth_test){ \
depth = bc.x*sa->z+bc.y*sb->z+bc.z*sc->z; \
pass_depth_test = ssr_testdepth(p.x, p.y, depth); \
} \
/*early stencil testing*/ \
if(stencil_test){ \
pass_stencil_test = ssr_teststencil(p.x, p.y, pass_depth_test); \
} \
discardif(!pass_depth_test || !pass_stencil_test); \
/*interpolate varying variables*/ \
ssrS_solveregs(&bc, IA, IB, IC); \
/*enter fragment shader*/ \
discard = !frag_shader(uniforms, &ssr_frag_in, out_color[0]); \
discardif(discard); \
/*put point*/ \
ssr_blendandputpoint(p.x, p.y, blend); \
/*write depth and stencil*/ \
if(write_depth) { \
ssr_writedepth(p.x, p.y, depth); \
} \
if(write_stencil) { \
ssr_writestencil(p.x, p.y, pass_depth_test, pass_stencil_test); \
} \
} \
}
#define FROM sa
#define TO sb
#define FROMK invkAC
#define TOK invkAB
#define OFFSET 0
#define SET_FROM_AND_TO \
from = (int)(invkAC * (p.y - sa->y) + sa->x); \
to = (int)(invkAB * (p.y - sa->y) + sa->x); \
RENDER_TRIANGLE
#define FROM sb
#define TO sc
#define FROMK invkAC
#define TOK invkBC
#define OFFSET 1
#define SET_FROM_AND_TO \
if (p.y == sb->y && sb->y == sc->y) { \
from = sc->x; \
to = sb->x; \
} \
else { \
from = (int)(invkAC * (p.y - sa->y) + sa->x); \
to = (int)(invkBC * (p.y - sb->y) + sb->x); \
}
RENDER_TRIANGLE
#undef discardif
#undef FROM
#undef TO
#undef FROMK
#undef TOK
#undef OFFSET
#undef SET_FROM_AND_TO
#undef RENDER_TRIANGLE
}
void ssrR_line(Vec4* CA, Vec4* CB, Vert* A, Vert* B, Program* program, UniformCollection* uniforms) {
ssr_assert(CA && CB && program && A && B && uniforms);
}
void ssrR_point(Vec4* CA, Vert* A, Program* program, UniformCollection* uniforms) {
ssr_assert(CA && program && A && uniforms);
}
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