#include "precompiled.h"
#pragma hdrstop

#include "tr_local.h"

static srfTriangles_t* g_skyDomeTri = NULL;
static const idMaterial* g_skyDomeMat = NULL;

static idCVar r_skyDome("r_skyDome", "1", CVAR_RENDERER | CVAR_BOOL, "render procedural skydome");
static idCVar r_skyDomeRadius("r_skyDomeRadius", "8192", CVAR_RENDERER | CVAR_FLOAT, "skydome radius (world units)");
static idCVar r_skyDomeRings("r_skyDomeRings", "24", CVAR_RENDERER | CVAR_INTEGER, "skydome vertical subdivisions");
static idCVar r_skyDomeSegments("r_skyDomeSegments", "48", CVAR_RENDERER | CVAR_INTEGER, "skydome horizontal subdivisions");

static idCVar r_skyClouds("r_skyClouds", "1", CVAR_RENDERER | CVAR_BOOL, "render automatic raymarched sky clouds");
static idCVar r_skyCloudZMin("r_skyCloudZMin", "2600", CVAR_RENDERER | CVAR_FLOAT, "sky cloud slab minimum world z");
static idCVar r_skyCloudZMax("r_skyCloudZMax", "7600", CVAR_RENDERER | CVAR_FLOAT, "sky cloud slab maximum world z");
static idCVar r_skyCloudScale("r_skyCloudScale", "0.00021", CVAR_RENDERER | CVAR_FLOAT, "sky cloud world noise scale");
static idCVar r_skyCloudCoverage("r_skyCloudCoverage", "0.30", CVAR_RENDERER | CVAR_FLOAT, "sky cloud coverage threshold, lower is denser");
static idCVar r_skyCloudDensity("r_skyCloudDensity", "0.5", CVAR_RENDERER | CVAR_FLOAT, "sky cloud density accumulation");
static idCVar r_skyCloudOpacity("r_skyCloudOpacity", "0.78", CVAR_RENDERER | CVAR_FLOAT, "sky cloud final opacity");
static idCVar r_skyCloudSeedOffset("r_skyCloudSeedOffset", "12000", CVAR_RENDERER | CVAR_FLOAT, "sky cloud world noise seed offset");
static idCVar r_skyCloudColor("r_skyCloudColor", "auto", CVAR_RENDERER, "sky cloud color override as 'r g b' in 0..1 or 0..255; auto samples the skydome");
static idCVar r_skyCloudWind("r_skyCloudWind", "55 -18", CVAR_RENDERER, "sky cloud scroll wind as world x y units per second");
static idCVar r_skyCloudVolume("r_skyCloudVolume", "0.65", CVAR_RENDERER | CVAR_FLOAT, "cheap cloud self-shadow and height shaping amount");
static idCVar r_skyFog("r_skyFog", "1", CVAR_RENDERER | CVAR_BOOL, "render sky horizon fog");
static idCVar r_skyFogOpacity("r_skyFogOpacity", "0.36", CVAR_RENDERER | CVAR_FLOAT, "sky horizon fog opacity");
static idCVar r_skyFogHeight("r_skyFogHeight", "0.30", CVAR_RENDERER | CVAR_FLOAT, "view ray z height where sky horizon fog fades out");
static idCVar r_skyFogPower("r_skyFogPower", "1.15", CVAR_RENDERER | CVAR_FLOAT, "sky horizon fog falloff power");

static void R_UploadSkyDomeMeshToVertexCache(srfTriangles_t* tri) {
	if (!tri) {
		return;
	}

	if (tri->ambientCache) {
		vertexCache.Free(tri->ambientCache);
		tri->ambientCache = 0;
	}

	if (tri->indexCache) {
		vertexCache.Free(tri->indexCache);
		tri->indexCache = 0;
	}

	vertexCache.Alloc(
		tri->verts,
		tri->numVerts * sizeof(tri->verts[0]),
		&tri->ambientCache
	);

	vertexCache.Alloc(
		tri->indexes,
		tri->numIndexes * sizeof(tri->indexes[0]),
		&tri->indexCache
	);
}

// Build a hemisphere, top half. Inside-facing draw.
static srfTriangles_t* R_BuildSkyDomeMesh(int rings, int segs, float radius) {
	rings = Max(rings, 4);
	segs = Max(segs, 8);

	const int vertsPerRing = segs + 1;
	const int numVerts = (rings + 1) * vertsPerRing;

	const int numQuads = rings * segs;
	const int numTris = numQuads * 2;
	const int numIndexes = numTris * 3;

	srfTriangles_t* tri = R_AllocStaticTriSurf();
	R_AllocStaticTriSurfVerts(tri, numVerts);
	R_AllocStaticTriSurfIndexes(tri, numIndexes);

	idDrawVert* v = tri->verts;
	glIndex_t* idx = tri->indexes;

	int vi = 0;

	for (int r = 0; r <= rings; r++) {
		const float t = (float)r / (float)rings;
		const float phi = t * idMath::HALF_PI;

		const float sinPhi = idMath::Sin(phi);
		const float cosPhi = idMath::Cos(phi);

		for (int s = 0; s <= segs; s++) {
			const float u = (float)s / (float)segs;
			const float theta = u * idMath::TWO_PI;

			const float sinTheta = idMath::Sin(theta);
			const float cosTheta = idMath::Cos(theta);

			idVec3 dir;
			dir.x = cosTheta * cosPhi;
			dir.y = sinTheta * cosPhi;
			dir.z = sinPhi;

			v[vi].xyz = dir * radius;

			float uu = idMath::ATan(dir.y, dir.x) / idMath::TWO_PI + 0.5f;
			float vv = idMath::ASin(idMath::ClampFloat(-1.0f, 1.0f, dir.z)) / idMath::PI + 0.5f;

			vv = 1.0f - vv;

			v[vi].st.x = uu;
			v[vi].st.y = vv;

			v[vi].normal = dir;
			v[vi].tangents[0].Set(-sinTheta, cosTheta, 0.0f);
			v[vi].tangents[1].Set(0.0f, 0.0f, 1.0f);

			v[vi].color[0] = 255;
			v[vi].color[1] = 255;
			v[vi].color[2] = 255;
			v[vi].color[3] = 255;

			vi++;
		}
	}

	int ii = 0;

	for (int r = 0; r < rings; r++) {
		for (int s = 0; s < segs; s++) {
			const int i0 = r * vertsPerRing + s;
			const int i1 = i0 + 1;
			const int i2 = (r + 1) * vertsPerRing + s;
			const int i3 = i2 + 1;

			idx[ii++] = i0;
			idx[ii++] = i2;
			idx[ii++] = i1;

			idx[ii++] = i1;
			idx[ii++] = i2;
			idx[ii++] = i3;
		}
	}

	tri->numVerts = numVerts;
	tri->numIndexes = numIndexes;

	R_BoundTriSurf(tri);

	R_UploadSkyDomeMeshToVertexCache(tri);

	return tri;
}

static idImage* R_GetSkyDomeImage() {
	if (!g_skyDomeMat || g_skyDomeMat->GetNumStages() <= 0) {
		return NULL;
	}

	const shaderStage_t* stage = g_skyDomeMat->GetStage(0);

	if (!stage || !stage->texture.image) {
		return NULL;
	}

	return stage->texture.image;
}

static void R_GetSkyAverageColor(float color[3]) {
	color[0] = 0.16f;
	color[1] = 0.28f;
	color[2] = 0.48f;

	idImage* skyImage = R_GetSkyDomeImage();

	if (!skyImage) {
		return;
	}

	skyImage->Bind();

	const float* average = skyImage->GetAverageColor();

	if (!average) {
		return;
	}

	color[0] = idMath::ClampFloat(0.03f, 1.0f, average[0]);
	color[1] = idMath::ClampFloat(0.03f, 1.0f, average[1]);
	color[2] = idMath::ClampFloat(0.03f, 1.0f, average[2]);
}

static void R_GetSkyCloudColor(float color[3]) {
	R_GetSkyAverageColor(color);

	float overrideColor[3];
	if (sscanf(r_skyCloudColor.GetString(), "%f %f %f", &overrideColor[0], &overrideColor[1], &overrideColor[2]) != 3) {
		return;
	}

	const bool byteColor = overrideColor[0] > 1.0f || overrideColor[1] > 1.0f || overrideColor[2] > 1.0f;
	const float scale = byteColor ? (1.0f / 255.0f) : 1.0f;
	color[0] = idMath::ClampFloat(0.0f, 1.0f, overrideColor[0] * scale);
	color[1] = idMath::ClampFloat(0.0f, 1.0f, overrideColor[1] * scale);
	color[2] = idMath::ClampFloat(0.0f, 1.0f, overrideColor[2] * scale);
}

static void RB_DrawSkyCloudOverlay(const viewDef_t* viewDef) {
	if (!viewDef) {
		return;
	}

	const bool drawClouds = r_skyClouds.GetBool();
	const bool drawFog = r_skyFog.GetBool() && r_skyFogOpacity.GetFloat() > 0.0f;

	if (!drawClouds && !drawFog) {
		return;
	}

	glSkyClouds_t clouds;
	memset(&clouds, 0, sizeof(clouds));

	R_GetSkyCloudColor(clouds.skyColor);
	R_GetSkyAverageColor(clouds.fogColor);
	clouds.opacity = drawClouds ? idMath::ClampFloat(0.0f, 1.0f, r_skyCloudOpacity.GetFloat()) : 0.0f;
	clouds.fogOpacity = drawFog ? idMath::ClampFloat(0.0f, 1.0f, r_skyFogOpacity.GetFloat()) : 0.0f;
	clouds.fogHeight = Max(r_skyFogHeight.GetFloat(), 0.01f);
	clouds.fogPower = Max(r_skyFogPower.GetFloat(), 0.25f);

	const idVec3& viewOrg = viewDef->renderView.vieworg;
	clouds.viewOrigin[0] = viewOrg.x;
	clouds.viewOrigin[1] = viewOrg.y;
	clouds.viewOrigin[2] = viewOrg.z;
	clouds.zMin = r_skyCloudZMin.GetFloat();
	clouds.zMax = Max(r_skyCloudZMax.GetFloat(), clouds.zMin + 64.0f);

	const idMat3& axis = viewDef->renderView.viewaxis;
	clouds.viewForward[0] = axis[0].x;
	clouds.viewForward[1] = axis[0].y;
	clouds.viewForward[2] = axis[0].z;
	clouds.viewRight[0] = -axis[1].x;
	clouds.viewRight[1] = -axis[1].y;
	clouds.viewRight[2] = -axis[1].z;
	clouds.viewUp[0] = axis[2].x;
	clouds.viewUp[1] = axis[2].y;
	clouds.viewUp[2] = axis[2].z;
	clouds.tanHalfFovX = idMath::Tan(DEG2RAD(viewDef->renderView.fov_x * 0.5f));
	clouds.tanHalfFovY = idMath::Tan(DEG2RAD(viewDef->renderView.fov_y * 0.5f));
	clouds.noiseScale = Max(r_skyCloudScale.GetFloat(), 0.00001f);
	clouds.coverage = idMath::ClampFloat(0.0f, 1.0f, r_skyCloudCoverage.GetFloat());
	clouds.density = drawClouds ? Max(r_skyCloudDensity.GetFloat(), 0.0f) : 0.0f;
	clouds.seedOffset = r_skyCloudSeedOffset.GetFloat();
	clouds.time = viewDef->renderView.time * 0.001f;
	clouds.wind[0] = 55.0f;
	clouds.wind[1] = -18.0f;
	sscanf(r_skyCloudWind.GetString(), "%f %f", &clouds.wind[0], &clouds.wind[1]);
	clouds.volume = idMath::ClampFloat(0.0f, 1.0f, r_skyCloudVolume.GetFloat());

	glDrawSkyCloudsQD3D12(&clouds);
}

void R_InitSkyDome() {
	if (g_skyDomeTri) {
		return;
	}

	g_skyDomeTri = R_BuildSkyDomeMesh(
		r_skyDomeRings.GetInteger(),
		r_skyDomeSegments.GetInteger(),
		r_skyDomeRadius.GetFloat()
	);
}

void R_ShutdownSkyDome() {
	if (g_skyDomeTri) {
		if (g_skyDomeTri->ambientCache) {
			vertexCache.Free(g_skyDomeTri->ambientCache);
			g_skyDomeTri->ambientCache = 0;
		}

		if (g_skyDomeTri->indexCache) {
			vertexCache.Free(g_skyDomeTri->indexCache);
			g_skyDomeTri->indexCache = 0;
		}

		R_FreeStaticTriSurf(g_skyDomeTri);
		g_skyDomeTri = NULL;
	}

	g_skyDomeMat = NULL;
}

static const idMaterial* R_GetSkyDomeMaterial() {
	return backEnd.viewDef->renderView.skyDomeMaterial;
}

void RB_DrawSkyDome(const viewDef_t* viewDef) {
	if (!r_skyDome.GetBool()) {
		return;
	}

	if (!g_skyDomeTri || !g_skyDomeTri->ambientCache || !g_skyDomeTri->indexCache) {
		return;
	}

	g_skyDomeMat = R_GetSkyDomeMaterial();

	if (!g_skyDomeMat) {
		return;
	}

	glDepthMask(GL_FALSE);
	glDisable(GL_CULL_FACE);

	glMatrixMode(GL_MODELVIEW);
	glPushMatrix();

	float mv[16];
	memcpy(mv, backEnd.viewDef->worldSpace.modelViewMatrix, sizeof(mv));

	mv[12] = 0.0f;
	mv[13] = 0.0f;
	mv[14] = 0.0f;

	glLoadMatrixf(mv);

	GL_SelectTexture(0);

	idImage* skyImage = R_GetSkyDomeImage();

	if (skyImage) {
		skyImage->Bind();
	}
	else {
		globalImages->whiteImage->Bind();
	}

	idDrawVert* verts = (idDrawVert*)vertexCache.Position(g_skyDomeTri->ambientCache);

	glEnableClientState(GL_VERTEX_ARRAY);
	glEnableClientState(GL_TEXTURE_COORD_ARRAY);

	glVertexPointer(
		3,
		GL_FLOAT,
		sizeof(idDrawVert),
		verts->xyz.ToFloatPtr()
	);

	glTexCoordPointer(
		2,
		GL_FLOAT,
		sizeof(idDrawVert),
		verts->st.ToFloatPtr()
	);

	glGeometryFlagf(GEOMETRY_FLAG_UNLIT + GEOMETRY_FLAG_SKYDOME);
	RB_DrawElementsWithCounters(g_skyDomeTri);
	RB_DrawSkyCloudOverlay(viewDef);
	glGeometryFlagf(GEOMETRY_FLAG_NONE);

	glPopMatrix();

	GL_State(GLS_DEFAULT);
	glDepthMask(GL_TRUE);
	glEnable(GL_CULL_FACE);

	glClear(GL_DEPTH_BUFFER_BIT);
}