Change fragment shader to utilize faster vec4 operations.
diff --git a/progs/demos/arbfslight.c b/progs/demos/arbfslight.c
index 30332a3..374de56 100644
--- a/progs/demos/arbfslight.c
+++ b/progs/demos/arbfslight.c
@@ -16,6 +16,7 @@
#include <stdio.h>
#include <stdlib.h>
+#include <math.h>
#include <GL/gl.h>
#include <GL/glut.h>
#include <GL/glext.h>
@@ -56,7 +57,16 @@
static PFNGLLINKPROGRAMARBPROC glLinkProgramARB = NULL;
static PFNGLUSEPROGRAMOBJECTARBPROC glUseProgramObjectARB = NULL;
static PFNGLGETUNIFORMLOCATIONARBPROC glGetUniformLocationARB = NULL;
-static PFNGLUNIFORM4FVARBPROC glUniform4fvARB = NULL;
+static PFNGLUNIFORM3FVARBPROC glUniform3fvARB = NULL;
+static PFNGLUNIFORM3FVARBPROC glUniform4fvARB = NULL;
+
+static void normalize (GLfloat *dst, const GLfloat *src)
+{
+ GLfloat len = sqrtf (src[0] * src[0] + src[1] * src[1] + src[2] * src[2]);
+ dst[0] = src[0] / len;
+ dst[1] = src[1] / len;
+ dst[2] = src[2] / len;
+}
static void Redisplay (void)
{
@@ -64,8 +74,11 @@
if (pixelLight)
{
+ GLfloat vec[3];
+
glUseProgramObjectARB (program);
- glUniform4fvARB (uLightPos, 1, lightPos);
+ normalize (vec, lightPos);
+ glUniform3fvARB (uLightPos, 1, vec);
glDisable(GL_LIGHTING);
}
else
@@ -186,24 +199,25 @@
static void Init (void)
{
- static const char *fragShaderText =
- "uniform vec4 lightPos;\n"
- "uniform vec4 diffuse;\n"
- "uniform vec4 specular;\n"
- "void main () {\n"
- " // Compute dot product of light direction and normal vector\n"
- " float dotProd;\n"
- " dotProd = clamp (dot (normalize (lightPos).xyz, normalize (gl_TexCoord[0]).xyz), 0.0, 1.0);\n"
- " // Compute diffuse and specular contributions\n"
- " gl_FragColor = diffuse * dotProd + specular * pow (dotProd, 20.0);\n"
- "}\n"
- ;
- static const char *vertShaderText =
- "void main () {\n"
- " gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
- " gl_TexCoord[0] = vec4 (gl_NormalMatrix * gl_Normal, 1.0);\n"
- "}\n"
- ;
+ static const char *fragShaderText =
+ "uniform vec3 lightPos;\n"
+ "uniform vec4 diffuse;\n"
+ "uniform vec4 specular;\n"
+ "varying vec3 normal;\n"
+ "void main () {\n"
+ " // Compute dot product of light direction and normal vector\n"
+ " float dotProd = max (dot (lightPos, normalize (normal)), 0.0);\n"
+ " // Compute diffuse and specular contributions\n"
+ " gl_FragColor = diffuse * dotProd + specular * pow (dotProd, 20.0);\n"
+ "}\n"
+ ;
+ static const char *vertShaderText =
+ "varying vec3 normal;\n"
+ "void main () {\n"
+ " gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
+ " normal = gl_NormalMatrix * gl_Normal;\n"
+ "}\n"
+ ;
if (!glutExtensionSupported ("GL_ARB_fragment_shader"))
{
@@ -234,7 +248,8 @@
glLinkProgramARB = (PFNGLLINKPROGRAMARBPROC) GETPROCADDRESS ("glLinkProgramARB");
glUseProgramObjectARB = (PFNGLUSEPROGRAMOBJECTARBPROC) GETPROCADDRESS ("glUseProgramObjectARB");
glGetUniformLocationARB = (PFNGLGETUNIFORMLOCATIONARBPROC) GETPROCADDRESS ("glGetUniformLocationARB");
- glUniform4fvARB = (PFNGLUNIFORM4FVARBPROC) GETPROCADDRESS ("glUniform4fvARB");
+ glUniform3fvARB = (PFNGLUNIFORM3FVARBPROC) GETPROCADDRESS ("glUniform3fvARB");
+ glUniform4fvARB = (PFNGLUNIFORM3FVARBPROC) GETPROCADDRESS ("glUniform4fvARB");
fragShader = glCreateShaderObjectARB (GL_FRAGMENT_SHADER_ARB);
glShaderSourceARB (fragShader, 1, &fragShaderText, NULL);
@@ -254,8 +269,8 @@
uDiffuse = glGetUniformLocationARB (program, "diffuse");
uSpecular = glGetUniformLocationARB (program, "specular");
- glUniform4fvARB (uDiffuse, 1, diffuse);
- glUniform4fvARB (uSpecular, 1, specular);
+ glUniform4fvARB (uDiffuse, 1, diffuse);
+ glUniform4fvARB (uSpecular, 1, specular);
glClearColor (0.3f, 0.3f, 0.3f, 0.0f);
glEnable (GL_DEPTH_TEST);