From 3d83d0fcfe68e1aa5437e7e557ac2ff214f9a0f6 Mon Sep 17 00:00:00 2001
From: bjorn <mail@bjornbyt.es>
Date: Thu, 9 Jun 2022 23:38:33 -0700
Subject: [PATCH] Pass:multimesh;

IT'S ALIVE
---
 src/api/l_graphics_pass.c       | 13 +++++++++
 src/modules/graphics/graphics.c | 50 +++++++++++++++++++++++----------
 src/modules/graphics/graphics.h |  1 +
 3 files changed, 49 insertions(+), 15 deletions(-)

diff --git a/src/api/l_graphics_pass.c b/src/api/l_graphics_pass.c
index 84c63e9d..7b7eaa17 100644
--- a/src/api/l_graphics_pass.c
+++ b/src/api/l_graphics_pass.c
@@ -519,6 +519,18 @@ static int l_lovrPassMesh(lua_State* L) {
   return 0;
 }
 
+static int l_lovrPassMultimesh(lua_State* L) {
+  Pass* pass = luax_checktype(L, 1, Pass);
+  Buffer* vertices = !lua_toboolean(L, 2) ? NULL : luax_totype(L, 2, Buffer);
+  Buffer* indices = luax_totype(L, 3, Buffer);
+  Buffer* draws = luax_checktype(L, 4, Buffer);
+  uint32_t count = luax_optu32(L, 5, 1);
+  uint32_t offset = luax_optu32(L, 6, 0);
+  uint32_t stride = luax_optu32(L, 7, 0);
+  lovrPassMultimesh(pass, vertices, indices, draws, count, offset, stride);
+  return 0;
+}
+
 static int l_lovrPassCompute(lua_State* L) {
   Pass* pass = luax_checktype(L, 1, Pass);
   Buffer* buffer = luax_totype(L, 2, Buffer);
@@ -720,6 +732,7 @@ const luaL_Reg lovrPass[] = {
   { "box", l_lovrPassBox },
   { "circle", l_lovrPassCircle },
   { "mesh", l_lovrPassMesh },
+  { "multimesh", l_lovrPassMultimesh },
 
   { "compute", l_lovrPassCompute },
 
diff --git a/src/modules/graphics/graphics.c b/src/modules/graphics/graphics.c
index 07ddeb0e..f5b3aad8 100644
--- a/src/modules/graphics/graphics.c
+++ b/src/modules/graphics/graphics.c
@@ -195,8 +195,6 @@ typedef struct {
   uint32_t count;
   uint32_t instances;
   uint32_t base;
-  Buffer* indirect;
-  uint32_t offset;
 } Draw;
 
 typedef struct {
@@ -2154,25 +2152,15 @@ static void lovrPassDraw(Pass* pass, Draw* draw) {
   flushBuiltins(pass, draw, shader);
   flushBuffers(pass, draw);
 
-  bool indexed = draw->index.buffer || draw->index.count > 0;
   uint32_t defaultCount = draw->index.count > 0 ? draw->index.count : draw->vertex.count;
   uint32_t count = draw->count > 0 ? draw->count : defaultCount;
   uint32_t instances = MAX(draw->instances, 1);
   uint32_t id = pass->drawCount & 0xff;
 
-  if (draw->indirect) {
-    trackBuffer(pass, draw->indirect, GPU_PHASE_INDIRECT, GPU_CACHE_INDIRECT);
-    if (indexed) {
-      gpu_draw_indirect_indexed(pass->stream, draw->indirect->gpu, draw->offset, count);
-    } else {
-      gpu_draw_indirect(pass->stream, draw->indirect->gpu, draw->offset, count);
-    }
+  if (draw->index.buffer || draw->index.count > 0) {
+    gpu_draw_indexed(pass->stream, count, instances, draw->start, draw->base, id);
   } else {
-    if (indexed) {
-      gpu_draw_indexed(pass->stream, count, instances, draw->start, draw->base, id);
-    } else {
-      gpu_draw(pass->stream, count, instances, draw->start, id);
-    }
+    gpu_draw(pass->stream, count, instances, draw->start, id);
   }
 
   pass->drawCount++;
@@ -2360,6 +2348,38 @@ void lovrPassMesh(Pass* pass, Buffer* vertices, Buffer* indices, float* transfor
   });
 }
 
+void lovrPassMultimesh(Pass* pass, Buffer* vertices, Buffer* indices, Buffer* draws, uint32_t count, uint32_t offset, uint32_t stride) {
+  lovrCheck(pass->info.type == PASS_RENDER, "This function can only be called on a render pass");
+  lovrCheck(offset % 4 == 0, "Multimesh draw buffer offset must be a multiple of 4");
+  uint32_t commandSize = indices ? 20 : 16;
+  stride = stride ? stride : commandSize;
+  uint32_t totalSize = stride * (count - 1) + commandSize;
+  lovrCheck(offset + totalSize < draws->size, "Multimesh draw range exceeds size of draw buffer");
+
+  Draw draw = (Draw) {
+    .mode = pass->pipeline->drawMode,
+    .vertex.buffer = vertices,
+    .index.buffer = indices
+  };
+
+  Shader* shader = pass->pipeline->shader;
+  lovrCheck(shader, "A custom Shader must be bound to draw a multimesh");
+
+  flushPipeline(pass, &draw, shader);
+  flushConstants(pass, shader);
+  flushBindings(pass, shader);
+  flushBuiltins(pass, &draw, shader);
+  flushBuffers(pass, &draw);
+
+  if (indices) {
+    gpu_draw_indirect_indexed(pass->stream, draws->gpu, offset, count, stride);
+  } else {
+    gpu_draw_indirect(pass->stream, draws->gpu, offset, count, stride);
+  }
+
+  trackBuffer(pass, draws, GPU_PHASE_INDIRECT, GPU_CACHE_INDIRECT);
+}
+
 void lovrPassCompute(Pass* pass, uint32_t x, uint32_t y, uint32_t z, Buffer* indirect, uint32_t offset) {
   lovrCheck(pass->info.type == PASS_COMPUTE, "This function can only be called on a compute pass");
 
diff --git a/src/modules/graphics/graphics.h b/src/modules/graphics/graphics.h
index 98d0da27..39dd44bc 100644
--- a/src/modules/graphics/graphics.h
+++ b/src/modules/graphics/graphics.h
@@ -406,6 +406,7 @@ void lovrPassPlane(Pass* pass, float* transform, uint32_t cols, uint32_t rows);
 void lovrPassBox(Pass* pass, float* transform);
 void lovrPassCircle(Pass* pass, float* transform, float angle1, float angle2, uint32_t segments);
 void lovrPassMesh(Pass* pass, Buffer* vertices, Buffer* indices, float* transform, uint32_t start, uint32_t count, uint32_t instances);
+void lovrPassMultimesh(Pass* pass, Buffer* vertices, Buffer* indices, Buffer* indirect, uint32_t count, uint32_t offset, uint32_t stride);
 void lovrPassCompute(Pass* pass, uint32_t x, uint32_t y, uint32_t z, Buffer* indirect, uint32_t offset);
 void lovrPassClearBuffer(Pass* pass, Buffer* buffer, uint32_t offset, uint32_t extent);
 void lovrPassClearTexture(Pass* pass, Texture* texture, float value[4], uint32_t layer, uint32_t layerCount, uint32_t level, uint32_t levelCount);