X-Git-Url: http://git.lukelau.me/?a=blobdiff_plain;f=billboardfrag.glsl;h=b4cfd511464569ea23c577cda41a5b261c7ba288;hb=c8b0a84bbafd306103b005e7e238b11a656dcba3;hp=840ec895609039c2989a77f69b2d56c12448e910;hpb=69b74f1d5e67236a5396b75628a6e1be0e501631;p=clouds.git

diff --git a/billboardfrag.glsl b/billboardfrag.glsl
index 840ec89..b4cfd51 100644
--- a/billboardfrag.glsl
+++ b/billboardfrag.glsl
@@ -3,7 +3,41 @@ uniform vec4 color;
 uniform sampler2D tex;
 in vec2 texCoord;
 out vec4 FragColor;
+uniform bool modulate;
+uniform bool debug;
+uniform bool debugColor;
+uniform float debugVal;
 void main() {
-  FragColor = texture(tex, texCoord).r * color;
+  if (debugColor) {
+    FragColor = color;
+    return;
+  }
+  if (debug) {
+    FragColor = mix(vec4(1, 1, 1, 0), vec4(1, 0, 0, 1), debugVal);
+    return;
+  }
+  // Cf = color from fragment, Ct = color from texture
+  // Cc = color from texture environment -- not set, defaults to (0,0,0,0)
+  // Af = alpha from fragment, At = alpha from texture
+  // C = output color, A = output alpha
+  float f = texture(tex, texCoord).r;
+  if (modulate) { 
+    // GL_MODULATE: C
+    // C = Cf * Ct
+    // A = Af * At
+    // the +0.06 is a hack to get lighter clouds!
+    // can be thought of as ambient light
+    FragColor = color * (f + 0.02);
+  } else {
+    // "That is, the colors in the frame buffer are multiplied by the
+    // attenuation ratio of the billboard texture and then the colors in
+    // the texture are added"
+    // GL_BLEND:
+    // C = Cf * (1-Ct) + Cc * Ct
+    // A = Af * At
+    vec3 C = color.rgb * (1 - f);
+    float A = color.a * f;
+    FragColor = vec4(C, A);
+  }
 }