vk: brush: support normalmaps for water surfaces

Adds missing tangents.

Fixes #655

ref/vk/TODO.md

@@ -1,3 +1,8 @@
+# 2023-11-17 E332
+- [-] backside emissive water polygons:
+    - adding them makes things worse in other parts of the level
+- [x] water normalmap support -- added missing tangents
+
 # 2023-11-16 E331
 - [x] Emissive waters
     - [x] add emissive water surface to polygon lights

ref/vk/shaders/ray_primary_hit.glsl

@@ -106,7 +106,6 @@ void primaryRayHit(rayQueryEXT rq, inout RayPayloadPrimary payload) {
 	payload.base_color_a *= color;
 	payload.emissive.rgb *= color.rgb;
 
-
 	if (ubo.ubo.debug_display_only == DEBUG_DISPLAY_DISABLED) {
 		// Nop
 	} else if (ubo.ubo.debug_display_only == DEBUG_DISPLAY_SURFHASH) {

ref/vk/vk_brush.c

@@ -322,8 +322,12 @@ static void brushComputeWaterPolys( compute_water_polys_t args ) {
 			poly_vertices[i].normal[1] = 0;
 			poly_vertices[i].normal[2] = 0;
 
+			poly_vertices[i].tangent[0] = 0;
+			poly_vertices[i].tangent[1] = 0;
+			poly_vertices[i].tangent[2] = 0;
+
 			if (i > 1) {
-				vec3_t e0, e1, normal;
+				vec3_t e0, e1, normal, tangent;
 				VectorSubtract( poly_vertices[i - 1].pos, poly_vertices[0].pos, e0 );
 				VectorSubtract( poly_vertices[i].pos, poly_vertices[0].pos, e1 );
 				CrossProduct( e1, e0, normal );
@@ -332,6 +336,13 @@ static void brushComputeWaterPolys( compute_water_polys_t args ) {
 				VectorAdd(normal, poly_vertices[i].normal, poly_vertices[i].normal);
 				VectorAdd(normal, poly_vertices[i - 1].normal, poly_vertices[i - 1].normal);
 
+				computeTangentE(tangent, e0, e1,
+					poly_vertices[0].gl_tc, poly_vertices[i-1].gl_tc, poly_vertices[i].gl_tc);
+
+				VectorAdd(tangent, poly_vertices[0].tangent, poly_vertices[0].tangent);
+				VectorAdd(tangent, poly_vertices[i].tangent, poly_vertices[i].tangent);
+				VectorAdd(tangent, poly_vertices[i - 1].tangent, poly_vertices[i - 1].tangent);
+
 				args.dst_indices[indices++] = (uint16_t)(vertices);
 				args.dst_indices[indices++] = (uint16_t)(vertices + i - 1);
 				args.dst_indices[indices++] = (uint16_t)(vertices + i);
@@ -345,6 +356,7 @@ static void brushComputeWaterPolys( compute_water_polys_t args ) {
 
 		for( int i = 0; i < p->numverts; i++ ) {
 			VectorNormalize(poly_vertices[i].normal);
+			VectorNormalize(poly_vertices[i].tangent);
 #if 0
 			//const float dot = DotProduct(poly_vertices[i].normal, args.warp->plane->normal);
 			//if (dot < 0.) {

ref/vk/vk_math.c

@@ -267,12 +267,9 @@ void Matrix4x4_ConcatScale3( matrix4x4 out, float x, float y, float z )
 	Matrix4x4_Concat( out, base, temp );
 }
 
-void computeTangent(vec3_t out_tangent, const vec3_t v0, const vec3_t v1, const vec3_t v2, const vec2_t uv0, const vec2_t uv1, const vec2_t uv2) {
-	vec3_t e1, e2;
+void computeTangentE(vec3_t out_tangent, const vec3_t e1, const vec3_t e2, const vec2_t uv0, const vec2_t uv1, const vec2_t uv2) {
 	vec2_t duv1, duv2;
 
-	VectorSubtract(v1, v0, e1);
-	VectorSubtract(v2, v0, e2);
 	Vector2Subtract(uv1, uv0, duv1);
 	Vector2Subtract(uv2, uv0, duv2);
 
@@ -287,6 +284,15 @@ void computeTangent(vec3_t out_tangent, const vec3_t v0, const vec3_t v1, const
 	out_tangent[2] = f * (duv2[1] * e1[2] - duv1[1] * e2[2]);
 }
 
+void computeTangent(vec3_t out_tangent, const vec3_t v0, const vec3_t v1, const vec3_t v2, const vec2_t uv0, const vec2_t uv1, const vec2_t uv2) {
+	vec3_t e1, e2;
+
+	VectorSubtract(v1, v0, e1);
+	VectorSubtract(v2, v0, e2);
+
+	computeTangentE(out_tangent, e1, e2, uv0, uv1, uv2);
+}
+
 void Matrix4x4_CreateFromVectors(matrix4x4 out, const vec3_t right, const vec3_t up, const vec3_t z, const vec3_t translate) {
 	out[0][0] = right[0];
 	out[1][0] = right[1];

ref/vk/vk_math.h

@@ -21,6 +21,7 @@ void Matrix4x4_CreateProjection(matrix4x4 out, float xMax, float xMin, float yMa
 void Matrix4x4_CreateOrtho(matrix4x4 m, float xLeft, float xRight, float yBottom, float yTop, float zNear, float zFar);
 void Matrix4x4_CreateModelview( matrix4x4 out );
 
+void computeTangentE(vec3_t out_tangent, const vec3_t e1, const vec3_t e2, const vec2_t uv0, const vec2_t uv1, const vec2_t uv2);
 void computeTangent(vec3_t out_tangent, const vec3_t v0, const vec3_t v1, const vec3_t v2, const vec2_t uv0, const vec2_t uv1, const vec2_t uv2);
 
 void Matrix4x4_CreateFromVectors(matrix4x4 out, const vec3_t right, const vec3_t up, const vec3_t z, const vec3_t translate);