Use custom opengl call for bloom fullscreen shader.

git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@15022 178a84e3-b1eb-0310-8ba1-8eac791a3b58

data/shaders/bloom.frag

@@ -2,10 +2,12 @@
 uniform sampler2D tex;
 uniform float low;
 
+in vec2 uv;
+
 void main()
 {
 	vec3 weights = vec3(0.2126, 0.7152, 0.0722); // ITU-R BT. 709
-	vec3 col = texture2D(tex, gl_TexCoord[0].xy).xyz;
+	vec3 col = texture2D(tex, uv).xyz;
 	float luma = dot(weights, col);
 
 	col *= smoothstep(low, 0.9, luma);

data/shaders/screenquad.vert

@@ -0,0 +1,10 @@
+#version 130
+
+in vec2 Position;
+in vec2 Texcoord;
+out vec2 uv;
+
+void main() {
+	uv = Texcoord;
+	gl_Position = vec4(Position, 0., 1.);
+}