MODERN: Add support for alpha brushes.

Fixes #630.

Author: dsvensson

src/cl_ents.c

@@ -181,7 +181,18 @@ void CL_AddEntityToList(visentlist_t* list, visentlist_entrytype_t vistype, enti
 
 		ent = &list->list[cl_visents.count].ent;
 		list->list[cl_visents.count].type = type;
-		list->list[cl_visents.count].distance = VectorDistanceQuick(cl.simorg, ent->origin);
+		if (vistype == visent_alpha) {
+			// Sort transparent entities based on closest point for stable back-to-front rendering.
+			vec3_t distance;
+			int i;
+			for (i = 0; i < 3; i++) {
+				distance[i] = r_refdef.vieworg[i] - ent->origin[i];
+				distance[i] -= bound(ent->model->mins[i], distance[i], ent->model->maxs[i]);
+			}
+			list->list[cl_visents.count].distance = DotProduct(distance, distance);
+		} else {
+			list->list[cl_visents.count].distance = VectorDistanceQuick(cl.simorg, ent->origin);
+		}
 		list->list[cl_visents.count].draw[vistype] = true;
 
 		ent->outlineScale = 0.5f * (r_refdef2.outlineBase + DotProduct(ent->origin, r_refdef2.outline_vpn));
@@ -233,6 +244,9 @@ void CL_AddEntity(entity_t *ent)
 		vistype = visent_firstpass;
 		ent->renderfx |= RF_NOSHADOW;
 	}
+	else if (ent->alpha > 0.0f && ent->alpha < 1.0f) {
+		vistype = visent_alpha;
+	}
 	else {
 		vistype = visent_normal;
 	}

src/glm_rsurf.c

@@ -389,15 +389,23 @@ static glm_worldmodel_req_t* GLM_NextBatchRequest(model_t* model, float alpha, i
 	glm_brushmodel_drawcall_t* drawcall = &drawcalls[current_drawcall];
 	float mvMatrix[16];
 
+	glm_brushmodel_drawcall_type desired_type = alpha == 0.0f ? opaque_world : alpha_surfaces;
+
 	R_GetModelviewMatrix(mvMatrix);
 
 	// If user has switched off caustics (or no texture), ignore
 	if (caustics) {
 		caustics &= ((R_ProgramCustomOptions(r_program_brushmodel) & DRAW_CAUSTIC_TEXTURES) == DRAW_CAUSTIC_TEXTURES);
 	}
 
-	// See if previous batch has same texture & matrix, if so just continue
-	if (drawcall->batch_count) {
+	if (drawcall->type != desired_type) {
+		drawcall = GL_FlushWorldModelBatch();
+		drawcall->type = desired_type;
+	}
+	else if (drawcall->batch_count && drawcall->type == opaque_world) {
+		// See if previous request has same texture & matrix, if so just continue
+		// as long as drawcall is not alpha as such requests must be drawn in the
+		// predetermined order.
 		req = &drawcall->worldmodel_requests[drawcall->batch_count - 1];
 
 		if (allow_duplicate && model == req->model && req->samplerMappingCount == num_textures && req->firstTexture == first_texture && drawcall->batch_count < MAX_WORLDMODEL_BATCH && isAlphaTested == req->isAlphaTested) {
@@ -765,12 +773,12 @@ void GLM_DrawBrushModel(entity_t* ent, qbool polygonOffset, qbool caustics)
 	glm_worldmodel_req_t* req = NULL;
 	model_t* model = ent->model;
 
-	if (GLM_DuplicatePreviousRequest(model, 1.0f, model->last_texture_chained - model->first_texture_chained + 1, model->first_texture_chained, polygonOffset, caustics)) {
+	if (GLM_DuplicatePreviousRequest(model, ent->alpha, model->last_texture_chained - model->first_texture_chained + 1, model->first_texture_chained, polygonOffset, caustics)) {
 		return;
 	}
 
 	if (model->drawflat_chain) {
-		req = GLM_NextBatchRequest(model, 1.0f, 0, 0, false, false, false, false);
+		req = GLM_NextBatchRequest(model, ent->alpha, 0, 0, false, false, false, false);
 
 		req = GLM_DrawFlatChain(req, model->drawflat_chain);
 
@@ -788,10 +796,10 @@ void GLM_DrawBrushModel(entity_t* ent, qbool polygonOffset, qbool caustics)
 			continue;
 		}
 
-		req = GLM_NextBatchRequest(model, 1.0f, 1, i, polygonOffset, caustics, false, tex->isAlphaTested);
+		req = GLM_NextBatchRequest(model, ent->alpha, 1, i, polygonOffset, caustics, false, tex->isAlphaTested);
 		tex = R_TextureAnimation(ent, tex);
 		if (!GLM_AssignTexture(i, tex)) {
-			req = GLM_NextBatchRequest(model, 1.0f, 1, i, polygonOffset, caustics, false, tex->isAlphaTested);
+			req = GLM_NextBatchRequest(model, ent->alpha, 1, i, polygonOffset, caustics, false, tex->isAlphaTested);
 			GLM_AssignTexture(i, tex);
 		}
 
@@ -842,12 +850,15 @@ static void GL_SortDrawCalls(glm_brushmodel_drawcall_t* drawcall)
 		}
 	}
 
-	qsort(drawcall->worldmodel_requests, drawcall->batch_count, sizeof(drawcall->worldmodel_requests[0]), GL_DrawCallComparison);
+	// Translucent bmodels are put into requests based on their distance from view and sorting here will break that order.
+	if (drawcall->type == opaque_world) {
+		qsort(drawcall->worldmodel_requests, drawcall->batch_count, sizeof(drawcall->worldmodel_requests[0]), GL_DrawCallComparison);
+	}
 
 	for (i = 0; i < drawcall->batch_count; ++i) {
 		glm_worldmodel_req_t* thisReq = &drawcall->worldmodel_requests[i];
 
-		drawcall->calls[i].alpha = thisReq->alpha;
+		drawcall->calls[i].alpha = thisReq->alpha == 0.0f ? 1.0f : thisReq->alpha;
 		drawcall->calls[i].flags = thisReq->flags;
 		memcpy(drawcall->calls[i].modelMatrix, thisReq->mvMatrix, sizeof(drawcall->calls[i].modelMatrix));
 		drawcall->calls[i].samplerBase = thisReq->samplerMappingBase;

src/glsl/draw_world.fragment.glsl

@@ -45,6 +45,7 @@ in vec4 UnClipped;
 
 in float mix_floor;
 in float mix_wall;
+in float alpha;
 
 layout(location=0) out vec4 frag_colour;
 #ifdef DRAW_GEOMETRY
@@ -232,11 +233,11 @@ void main()
 		texColor = vec4(mix(texColor.rgb, texColor.rgb + lumaColor.rgb, min(1, Flags & EZQ_SURFACE_HAS_LUMA)), texColor.a);
 #endif
 		texColor = applyColorTinting(texColor);
-		frag_colour = vec4(lmColor.rgb, 1) * texColor;
+		frag_colour = vec4(lmColor.rgb * alpha, alpha) * texColor;
 #if defined(DRAW_LUMA_TEXTURES) && defined(DRAW_LUMA_TEXTURES_FB)
 		lumaColor = applyColorTinting(lumaColor);
 		frag_colour = vec4(mix(frag_colour.rgb, frag_colour.rgb + lumaColor.rgb, min(1, Flags & EZQ_SURFACE_HAS_LUMA)), frag_colour.a);
-		frag_colour = vec4(mix(frag_colour.rgb, lumaColor.rgb, min(1, Flags & EZQ_SURFACE_HAS_FB) * lumaColor.a), frag_colour.a);
+		frag_colour = vec4(mix(frag_colour.rgb, lumaColor.rgb * alpha, min(1, Flags & EZQ_SURFACE_HAS_FB) * lumaColor.a), frag_colour.a);
 #elif !defined(DRAW_LUMA_TEXTURES) && defined(DRAW_LUMA_TEXTURES_FB)
 		// GL_DECAL
 		lumaColor = applyColorTinting(lumaColor);

src/glsl/draw_world.vertex.glsl

@@ -36,6 +36,7 @@ layout(std140, binding = EZQ_GL_BINDINGPOINT_WORLDMODEL_SURFACES) buffer surface
 
 out float mix_floor;
 out float mix_wall;
+out float alpha;
 
 layout(std140, binding=EZQ_GL_BINDINGPOINT_BRUSHMODEL_DRAWDATA) buffer WorldCvars {
 	WorldDrawInfo drawInfo[];
@@ -51,6 +52,7 @@ void main()
 	float materialArrayIndex = samplerMapping[drawInfo[_instanceId].samplerBase + materialNumber].layer;
 	int drawCallFlags = drawInfo[_instanceId].drawFlags;
 	int textureFlags = samplerMapping[drawInfo[_instanceId].samplerBase + materialNumber].flags;
+	alpha = drawInfo[_instanceId].alpha;
 
 	gl_Position = projectionMatrix * drawInfo[_instanceId].mvMatrix * vec4(position, 1.0);
 #ifdef DRAW_GEOMETRY