d3dx9_36 [try 2]: Save multiplications and divisions to improve performance

[David Adam]

Hi,

I added a test with 65000 sides. All the test pass with a native d3dx9_36
dll.
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From b347a300814cfa032905584e06384c17ee39ad56 Mon Sep 17 00:00:00 2001
From: David Adam <david.adam.cnrs at gmail.com>
Date: Thu, 25 Jun 2015 11:11:29 -1000
Subject: d3dx9_36: Save multiplications and divisions to improve performance

---
 dlls/d3dx9_36/mesh.c       | 10 ++++++----
 dlls/d3dx9_36/tests/mesh.c | 11 +++++++----
 2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/dlls/d3dx9_36/mesh.c b/dlls/d3dx9_36/mesh.c
index 746b479..5be54d2 100644
--- a/dlls/d3dx9_36/mesh.c
+++ b/dlls/d3dx9_36/mesh.c
@@ -4563,7 +4563,7 @@ HRESULT WINAPI D3DXCreatePolygon(struct IDirect3DDevice9 *device, float length,
     struct vertex *vertices;
     WORD (*faces)[3];
     DWORD (*adjacency_buf)[3];
-    float scale;
+    float angle, scale;
     unsigned int i;
 
     TRACE("device %p, length %f, sides %u, mesh %p, adjacency %p.\n",
@@ -4591,7 +4591,9 @@ HRESULT WINAPI D3DXCreatePolygon(struct IDirect3DDevice9 *device, float length,
         return hr;
     }
 
-    scale = 0.5f * length / sinf(D3DX_PI / sides);
+    angle = D3DX_PI / sides;
+    scale = 0.5f * length / sinf(angle);
+    angle *= 2.0f;
 
     vertices[0].position.x = 0.0f;
     vertices[0].position.y = 0.0f;
@@ -4602,8 +4604,8 @@ HRESULT WINAPI D3DXCreatePolygon(struct IDirect3DDevice9 *device, float length,
 
     for (i = 0; i < sides; ++i)
     {
-        vertices[i + 1].position.x = cosf(2.0f * D3DX_PI * i / sides) * scale;
-        vertices[i + 1].position.y = sinf(2.0f * D3DX_PI * i / sides) * scale;
+        vertices[i + 1].position.x = cosf(angle * i) * scale;
+        vertices[i + 1].position.y = sinf(angle * i) * scale;
         vertices[i + 1].position.z = 0.0f;
         vertices[i + 1].normal.x = 0.0f;
         vertices[i + 1].normal.y = 0.0f;
diff --git a/dlls/d3dx9_36/tests/mesh.c b/dlls/d3dx9_36/tests/mesh.c
index dac0f60..2a3ad2b 100644
--- a/dlls/d3dx9_36/tests/mesh.c
+++ b/dlls/d3dx9_36/tests/mesh.c
@@ -2605,12 +2605,14 @@ static void D3DXCreateBoxTest(void)
 static BOOL compute_polygon(struct mesh *mesh, float length, unsigned int sides)
 {
     unsigned int i;
-    float scale;
+    float angle, scale;
 
     if (!new_mesh(mesh, sides + 1, sides))
         return FALSE;
 
-    scale = 0.5f * length / sinf(D3DX_PI / sides);
+    angle = D3DX_PI / sides;
+    scale = 0.5f * length / sinf(angle);
+    angle *= 2.0f;
 
     mesh->vertices[0].position.x = 0.0f;
     mesh->vertices[0].position.y = 0.0f;
@@ -2621,8 +2623,8 @@ static BOOL compute_polygon(struct mesh *mesh, float length, unsigned int sides)
 
     for (i = 0; i < sides; ++i)
     {
-        mesh->vertices[i + 1].position.x = cosf(2.0f * D3DX_PI * i / sides) * scale;
-        mesh->vertices[i + 1].position.y = sinf(2.0f * D3DX_PI * i / sides) * scale;
+        mesh->vertices[i + 1].position.x = cosf(angle * i) * scale;
+        mesh->vertices[i + 1].position.y = sinf(angle * i) * scale;
         mesh->vertices[i + 1].position.z = 0.0f;
         mesh->vertices[i + 1].normal.x = 0.0f;
         mesh->vertices[i + 1].normal.y = 0.0f;
@@ -2750,6 +2752,7 @@ static void D3DXCreatePolygonTest(void)
     test_polygon(device, 10.0f, 5);
     test_polygon(device, 10.0f, 10);
     test_polygon(device, 20.0f, 10);
+    test_polygon(device, 20.0f, 65000);
 
     IDirect3DDevice9_Release(device);
     IDirect3D9_Release(d3d);
-- 
2.1.4