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-rw-r--r--progs/glsl/twoside.c44
1 files changed, 28 insertions, 16 deletions
diff --git a/progs/glsl/twoside.c b/progs/glsl/twoside.c
index 672a00491e..06488bd175 100644
--- a/progs/glsl/twoside.c
+++ b/progs/glsl/twoside.c
@@ -26,27 +26,39 @@ static GLuint fragShader;
static GLuint vertShader;
static GLuint program;
static GLint win = 0;
-static GLboolean anim = 0*GL_TRUE;
-static GLboolean DetermineInFragProg = GL_TRUE;
-static GLfloat Xrot = 30.0f;
+static GLboolean anim;
+static GLboolean DetermineFacingInFragProg;
+static GLfloat Xrot;
static GLint u_fragface;
-static GLenum FrontWinding = GL_CCW;
+static GLenum FrontWinding;
static int prevTime = 0;
-static const GLfloat Red[4] = {1, 0, 0, 0};
+static const GLfloat Red[4] = {1, 0, 0, 1};
static const GLfloat Green[4] = {0, 1, 0, 0};
static void
+SetDefaults(void)
+{
+ DetermineFacingInFragProg = GL_TRUE;
+ FrontWinding = GL_CCW;
+ Xrot = 30;
+ anim = 0;
+ glutIdleFunc(NULL);
+}
+
+
+static void
Redisplay(void)
{
+ const int sections = 20;
int i;
float radius = 2;
glFrontFace(FrontWinding);
- if (DetermineInFragProg) {
+ if (DetermineFacingInFragProg) {
glUniform1i_func(u_fragface, 1);
glDisable(GL_VERTEX_PROGRAM_TWO_SIDE);
}
@@ -64,8 +76,8 @@ Redisplay(void)
glBegin(GL_TRIANGLE_STRIP);
glColor4fv(Red);
glSecondaryColor3fv_func(Green);
- for (i = 0; i < 20; i++) {
- float a = i / 19.0 * M_PI * 2.0;
+ for (i = 0; i <= sections; i++) {
+ float a = (float) i / (sections) * M_PI * 2.0;
float x = radius * cos(a);
float y = radius * sin(a);
glVertex3f(x, -1, y);
@@ -139,17 +151,15 @@ Key(unsigned char key, int x, int y)
break;
case 'f':
printf("Using frag shader gl_FrontFacing\n");
- DetermineInFragProg = GL_TRUE;
+ DetermineFacingInFragProg = GL_TRUE;
break;
case 'v':
printf("Using vert shader Two-sided lighting\n");
- DetermineInFragProg = GL_FALSE;
+ DetermineFacingInFragProg = GL_FALSE;
break;
case 'r':
/* reset */
- Xrot = 30;
- anim = 0;
- glutIdleFunc(NULL);
+ SetDefaults();
break;
case 's':
Xrot += 5;
@@ -182,14 +192,16 @@ Init(void)
static const char *fragShaderText =
"uniform bool fragface; \n"
"void main() { \n"
-#if 0
+#if 1
" if (!fragface || gl_FrontFacing) { \n"
" gl_FragColor = gl_Color; \n"
" } \n"
" else { \n"
+ " // note: dim green to help debug \n"
" gl_FragColor = 0.8 * gl_SecondaryColor; \n"
" } \n"
#else
+ /* DEBUG CODE */
" bool f = gl_FrontFacing; \n"
" if (f) { \n"
" gl_FragColor = vec4(1.0, 0.0, 0.0, 0.0); \n"
@@ -197,8 +209,6 @@ Init(void)
" else { \n"
" gl_FragColor = vec4(0.0, 1.0, 0.0, 0.0); \n"
" } \n"
- " //float g = float(gl_FrontFacing) * 0.5 + 0.5; \n"
- " //gl_FragColor = vec4(g); \n"
#endif
"} \n";
static const char *vertShaderText =
@@ -241,6 +251,8 @@ Init(void)
assert(glIsShader_func(vertShader));
glEnable(GL_DEPTH_TEST);
+
+ SetDefaults();
}