Henri Verbeet : wined3d: Use clamp() instead of max() for calculating the clamped cosine in the ffp lighting calculations.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: ff6ce4c669ac901abdc9664d891b4b6d044df295
URL:    http://source.winehq.org/git/wine.git/?a=commit;h=ff6ce4c669ac901abdc9664d89...

Author: Henri Verbeet 
Date:   Wed Sep  4 08:56:43 2013 +0200

wined3d: Use clamp() instead of max() for calculating the clamped cosine in the ffp lighting calculations.

On typical hardware, the clamp() would be an instruction modifier, while the
max() would need an extra instruction.

---

dlls/wined3d/glsl_shader.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/dlls/wined3d/glsl_shader.c b/dlls/wined3d/glsl_shader.c
index 740e100..280ec20 100644
--- a/dlls/wined3d/glsl_shader.c
+++ b/dlls/wined3d/glsl_shader.c
@@ -4940,7 +4940,7 @@ static void shader_glsl_ffp_vertex_lighting(struct wined3d_shader_buffer *buffer
                 if (!settings->normal)
                     break;
                 shader_addline(buffer, "dir = normalize(dir);\n");
-                shader_addline(buffer, "diffuse += (max(0.0, dot(dir, normal))"
+                shader_addline(buffer, "diffuse += (clamp(dot(dir, normal), 0.0, 1.0)"
                         " * gl_LightSource[%u].diffuse.xyz) / att;\n", i);
                 if (settings->localviewer)
                     shader_addline(buffer, "t = dot(normal, normalize(dir - normalize(ec_pos.xyz)));\n");
@@ -4965,7 +4965,7 @@ static void shader_glsl_ffp_vertex_lighting(struct wined3d_shader_buffer *buffer
                 shader_addline(buffer, "ambient += gl_LightSource[%u].ambient.xyz * att;\n", i);
                 if (!settings->normal)
                     break;
-                shader_addline(buffer, "diffuse += (max(0.0, dot(dir, normal))"
+                shader_addline(buffer, "diffuse += (clamp(dot(dir, normal), 0.0, 1.0)"
                         " * gl_LightSource[%u].diffuse.xyz) * att;\n", i);
                 if (settings->localviewer)
                     shader_addline(buffer, "t = dot(normal, normalize(dir - normalize(ec_pos.xyz)));\n");
@@ -4980,7 +4980,8 @@ static void shader_glsl_ffp_vertex_lighting(struct wined3d_shader_buffer *buffer
                 if (!settings->normal)
                     break;
                 shader_addline(buffer, "dir = normalize(gl_LightSource[%u].position.xyz);\n", i);
-                shader_addline(buffer, "diffuse += max(0.0, dot(dir, normal)) * gl_LightSource[%u].diffuse.xyz;\n", i);
+                shader_addline(buffer, "diffuse += clamp(dot(dir, normal), 0.0, 1.0)"
+                        " * gl_LightSource[%u].diffuse.xyz;\n", i);
                 shader_addline(buffer, "t = dot(normal, gl_LightSource[%u].halfVector.xyz);\n", i);
                 shader_addline(buffer, "if (t > 0.0) specular += pow(t, gl_FrontMaterial.shininess)"
                         " * gl_LightSource[%u].specular;\n", i);