konsofren: kon_lightPass, point and spot lights from the depth buffer

2 files changed, 149 insertions, 0 deletions

diff --git a/kon/konmath.h b/kon/konmath.h
index 44f6571..f8aeceb 100644
--- a/kon/konmath.h
+++ b/kon/konmath.h
@@ -124,6 +124,40 @@ static inline kon_mat4_t kon_mat4Mul(kon_mat4_t a, kon_mat4_t b) {
 	return r;
 }
 
+/* the matrix that undoes m. returns the identity and sets *ok to 0 if m can't be undone, ok can be NULL */
+static inline kon_mat4_t kon_mat4Inverse(kon_mat4_t a, int *ok) {
+	const float *m = a.m;
+	kon_mat4_t r;
+	float *o = r.m, det;
+	int i;
+
+	o[0] = m[5] * m[10] * m[15] - m[5] * m[11] * m[14] - m[9] * m[6] * m[15] + m[9] * m[7] * m[14] + m[13] * m[6] * m[11] - m[13] * m[7] * m[10];
+	o[4] = -m[4] * m[10] * m[15] + m[4] * m[11] * m[14] + m[8] * m[6] * m[15] - m[8] * m[7] * m[14] - m[12] * m[6] * m[11] + m[12] * m[7] * m[10];
+	o[8] = m[4] * m[9] * m[15] - m[4] * m[11] * m[13] - m[8] * m[5] * m[15] + m[8] * m[7] * m[13] + m[12] * m[5] * m[11] - m[12] * m[7] * m[9];
+	o[12] = -m[4] * m[9] * m[14] + m[4] * m[10] * m[13] + m[8] * m[5] * m[14] - m[8] * m[6] * m[13] - m[12] * m[5] * m[10] + m[12] * m[6] * m[9];
+	o[1] = -m[1] * m[10] * m[15] + m[1] * m[11] * m[14] + m[9] * m[2] * m[15] - m[9] * m[3] * m[14] - m[13] * m[2] * m[11] + m[13] * m[3] * m[10];
+	o[5] = m[0] * m[10] * m[15] - m[0] * m[11] * m[14] - m[8] * m[2] * m[15] + m[8] * m[3] * m[14] + m[12] * m[2] * m[11] - m[12] * m[3] * m[10];
+	o[9] = -m[0] * m[9] * m[15] + m[0] * m[11] * m[13] + m[8] * m[1] * m[15] - m[8] * m[3] * m[13] - m[12] * m[1] * m[11] + m[12] * m[3] * m[9];
+	o[13] = m[0] * m[9] * m[14] - m[0] * m[10] * m[13] - m[8] * m[1] * m[14] + m[8] * m[2] * m[13] + m[12] * m[1] * m[10] - m[12] * m[2] * m[9];
+	o[2] = m[1] * m[6] * m[15] - m[1] * m[7] * m[14] - m[5] * m[2] * m[15] + m[5] * m[3] * m[14] + m[13] * m[2] * m[7] - m[13] * m[3] * m[6];
+	o[6] = -m[0] * m[6] * m[15] + m[0] * m[7] * m[14] + m[4] * m[2] * m[15] - m[4] * m[3] * m[14] - m[12] * m[2] * m[7] + m[12] * m[3] * m[6];
+	o[10] = m[0] * m[5] * m[15] - m[0] * m[7] * m[13] - m[4] * m[1] * m[15] + m[4] * m[3] * m[13] + m[12] * m[1] * m[7] - m[12] * m[3] * m[5];
+	o[14] = -m[0] * m[5] * m[14] + m[0] * m[6] * m[13] + m[4] * m[1] * m[14] - m[4] * m[2] * m[13] - m[12] * m[1] * m[6] + m[12] * m[2] * m[5];
+	o[3] = -m[1] * m[6] * m[11] + m[1] * m[7] * m[10] + m[5] * m[2] * m[11] - m[5] * m[3] * m[10] - m[9] * m[2] * m[7] + m[9] * m[3] * m[6];
+	o[7] = m[0] * m[6] * m[11] - m[0] * m[7] * m[10] - m[4] * m[2] * m[11] + m[4] * m[3] * m[10] + m[8] * m[2] * m[7] - m[8] * m[3] * m[6];
+	o[11] = -m[0] * m[5] * m[11] + m[0] * m[7] * m[9] + m[4] * m[1] * m[11] - m[4] * m[3] * m[9] - m[8] * m[1] * m[7] + m[8] * m[3] * m[5];
+	o[15] = m[0] * m[5] * m[10] - m[0] * m[6] * m[9] - m[4] * m[1] * m[10] + m[4] * m[2] * m[9] + m[8] * m[1] * m[6] - m[8] * m[2] * m[5];
+
+	det = m[0] * o[0] + m[1] * o[4] + m[2] * o[8] + m[3] * o[12];
+	if (det > -1.0e-20f && det < 1.0e-20f) {
+		if (ok) *ok = 0;
+		return kon_mat4Identity();
+	}
+	for (i = 0; i < 16; i++) o[i] /= det;
+	if (ok) *ok = 1;
+	return r;
+}
+
 static inline kon_vec4_t kon_mat4MulVec4(kon_mat4_t m, kon_vec4_t v) {
 	return (kon_vec4_t){
 		m.m[0] * v.x + m.m[4] * v.y + m.m[8]  * v.z + m.m[12] * v.w,
diff --git a/kon/konsofren.h b/kon/konsofren.h
index 4e29e56..6cca535 100644
--- a/kon/konsofren.h
+++ b/kon/konsofren.h
@@ -249,6 +249,26 @@ void kon_drawMesh(kon_framebuffer_t *fb, kon_mat4_t viewProjection, kon_mat4_t m
 int kon_drawBillboard(kon_framebuffer_t *fb, kon_mat4_t viewProjection, kon_vec3_t position, float width, float height,
 		const kon_image *image, kon_rect_t src, float brightness, kon_renderFlags_t flags);
 
+/*** lights that sit in the world ***/
+
+/* a light with a place. with cone 0 it shines all around, otherwise it is a spot light like a flashlight pointing along direction */
+typedef struct kon_pointLight {
+	kon_vec3_t position;
+	uint32_t color;       /* 0xFFRRGGBB, alpha is ignored */
+	float radius;         /* it reaches nothing farther than this */
+	float intensity;      /* 1 is full strength, more than that lights things brighter than they were drawn */
+	kon_vec3_t direction; /* spot lights only, the way it points */
+	float cone;           /* spot lights only, how wide it is from the middle to the edge in radians, 0 for a light that shines all around */
+	float soft;           /* spot lights only, 0 to 1, how much of the cone fades out at the edge */
+} kon_pointLight_t;
+
+/* lights what is already drawn, after everything with depth is in and before the screen elements. every pixel that has depth gets
+   color * (ambient + the light of every light that reaches it). draw the scene with light.ambient 1 and intensity 0 so it still has
+   its plain colors, this makes it dark and then lights it. it knows where things are but not which way they face, and it has no
+   shadows: light goes through walls, so keep the radius of a light inside its room. it costs about one pass over the screen plus a bit
+   for every light that is close. needs the depth buffer, so draw with KON_RENDER_DEPTH */
+void kon_lightPass(kon_framebuffer_t *fb, kon_mat4_t viewProjection, const kon_pointLight_t *lights, int count, float ambient);
+
 /* cube from -1 to 1 with every face mapped to the whole texture */
 extern const kon_mesh_t kon_cubeMesh;
 
@@ -1652,6 +1672,101 @@ int kon_drawBillboard(kon_framebuffer_t *fb, kon_mat4_t viewProjection, kon_vec3
 	return 1;
 }
 
+/*** light pass ***/
+
+typedef struct kon_lightSetup_ {
+	float x, y, z, radius, invRadius, intensity, r, g, b;
+	float dx, dy, dz, cosOuter, cosRange;
+	int spot;
+} kon_lightSetup_t;
+
+void kon_lightPass(kon_framebuffer_t *fb, kon_mat4_t viewProjection, const kon_pointLight_t *lights, int count, float ambient) {
+	enum { MAX_LIGHTS = 32 };
+	kon_lightSetup_t set[MAX_LIGHTS];
+	kon_mat4_t inv;
+	int used = 0, i, ok, px, py;
+	float ndcStepX, ndcStepY;
+
+	if (!fb || !fb->depth || !lights) return;
+	inv = kon_mat4Inverse(viewProjection, &ok);
+	if (!ok) return;
+	if (ambient < 0.0f) ambient = 0.0f;
+
+	for (i = 0; i < count && used < MAX_LIGHTS; i++) {
+		const kon_pointLight_t *l = &lights[i];
+		kon_lightSetup_t *s = &set[used];
+
+		if (l->radius <= 0.0f || l->intensity <= 0.0f) continue;
+		s->x = l->position.x; s->y = l->position.y; s->z = l->position.z;
+		s->radius = l->radius;
+		s->invRadius = 1.0f / l->radius;
+		s->intensity = l->intensity;
+		s->r = (float)((l->color >> 16) & 255) / 255.0f;
+		s->g = (float)((l->color >> 8) & 255) / 255.0f;
+		s->b = (float)(l->color & 255) / 255.0f;
+		s->spot = l->cone > 0.0f;
+		if (s->spot) {
+			float len = sqrtf(l->direction.x * l->direction.x + l->direction.y * l->direction.y + l->direction.z * l->direction.z);
+			float soft = kon_clamp(l->soft, 0.0f, 1.0f), inner = l->cone * (1.0f - soft);
+
+			if (len < 1.0e-6f) continue;
+			s->dx = l->direction.x / len; s->dy = l->direction.y / len; s->dz = l->direction.z / len;
+			s->cosOuter = cosf(l->cone);
+			s->cosRange = cosf(inner) - s->cosOuter;
+			if (s->cosRange < 1.0e-4f) s->cosRange = 1.0e-4f;
+		}
+		used++;
+	}
+
+	ndcStepX = 2.0f / (float)fb->width;
+	ndcStepY = 2.0f / (float)fb->height;
+	for (py = 0; py < fb->height; py++) {
+		float ndcY = 1.0f - ((float)py + 0.5f) * ndcStepY;
+
+		for (px = 0; px < fb->width; px++) {
+			int index = py * fb->width + px;
+			float z = fb->depth[index], ndcX, wx, wy, wz, ww, level[3], inverseW;
+			uint32_t c;
+			int k, r, g, b;
+
+			if (z >= 1.0f) continue;
+			ndcX = ((float)px + 0.5f) * ndcStepX - 1.0f;
+			wx = inv.m[0] * ndcX + inv.m[4] * ndcY + inv.m[8] * z + inv.m[12];
+			wy = inv.m[1] * ndcX + inv.m[5] * ndcY + inv.m[9] * z + inv.m[13];
+			wz = inv.m[2] * ndcX + inv.m[6] * ndcY + inv.m[10] * z + inv.m[14];
+			ww = inv.m[3] * ndcX + inv.m[7] * ndcY + inv.m[11] * z + inv.m[15];
+			inverseW = 1.0f / ww;
+			wx *= inverseW; wy *= inverseW; wz *= inverseW;
+
+			level[0] = level[1] = level[2] = ambient;
+			for (k = 0; k < used; k++) {
+				const kon_lightSetup_t *s = &set[k];
+				float dx = wx - s->x, dy = wy - s->y, dz = wz - s->z, d2 = dx * dx + dy * dy + dz * dz, d, fall, amount;
+
+				if (d2 >= s->radius * s->radius) continue;
+				d = sqrtf(d2);
+				fall = 1.0f - d * s->invRadius;
+				amount = fall * fall * s->intensity;
+				if (s->spot) {
+					float along = d > 1.0e-6f ? (dx * s->dx + dy * s->dy + dz * s->dz) / d : 1.0f, edge = (along - s->cosOuter) / s->cosRange;
+
+					if (edge <= 0.0f) continue;
+					if (edge < 1.0f) amount *= edge * edge * (3.0f - 2.0f * edge);
+				}
+				level[0] += amount * s->r;
+				level[1] += amount * s->g;
+				level[2] += amount * s->b;
+			}
+
+			c = fb->data[index];
+			r = (int)((float)((c >> 16) & 255) * level[0]);
+			g = (int)((float)((c >> 8) & 255) * level[1]);
+			b = (int)((float)(c & 255) * level[2]);
+			fb->data[index] = 0xFF000000u | (uint32_t)(r > 255 ? 255 : r) << 16 | (uint32_t)(g > 255 ? 255 : g) << 8 | (uint32_t)(b > 255 ? 255 : b);
+		}
+	}
+}
+
 #endif /* KONSOFREN_3D */
 
 #endif /* end of KONSOFREN_IMPLEMENTATION */