Simplify text shader

2 files changed, 31 insertions, 36 deletions

diff --git a/res/text.f.glsl b/res/text.f.glsl
index 532cf929..70ad3d19 100644
--- a/res/text.f.glsl
+++ b/res/text.f.glsl
@@ -13,19 +13,18 @@
 // limitations under the License.
 #version 330 core
 in vec2 TexCoords;
-in vec3 fg;
-in vec4 bg;
-flat in int background;
+flat in vec3 fg;
+flat in vec4 bg;
+uniform int backgroundPass;
 
 layout(location = 0, index = 0) out vec4 color;
 layout(location = 0, index = 1) out vec4 alphaMask;
 
-uniform float bgOpacity;
 uniform sampler2D mask;
 
 void main()
 {
-    if (background != 0) {
+    if (backgroundPass != 0) {
         if (bg.a == 0.0)
             discard;
 
diff --git a/res/text.v.glsl b/res/text.v.glsl
index 32aee5ac..369e7c7e 100644
--- a/res/text.v.glsl
+++ b/res/text.v.glsl
@@ -12,67 +12,63 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 #version 330 core
-layout (location = 0) in vec2 position;
-
 // Cell properties
-layout (location = 1) in vec2 gridCoords;
+layout (location = 0) in vec2 gridCoords;
 
 // glyph properties
-layout (location = 2) in vec4 glyph;
+layout (location = 1) in vec4 glyph;
 
 // uv mapping
-layout (location = 3) in vec4 uv;
+layout (location = 2) in vec4 uv;
 
 // text fg color
-layout (location = 4) in vec3 textColor;
+layout (location = 3) in vec3 textColor;
 
 // Background color
-layout (location = 5) in vec4 backgroundColor;
+layout (location = 4) in vec4 backgroundColor;
 
 out vec2 TexCoords;
-out vec3 fg;
-out vec4 bg;
+flat out vec3 fg;
+flat out vec4 bg;
 
 // Terminal properties
-uniform vec2 termDim;
 uniform vec2 cellDim;
+uniform vec4 projection;
 
 uniform int backgroundPass;
 
-// Orthographic projection
-uniform mat4 projection;
-flat out int background;
 
 void main()
 {
-    vec2 glyphOffset = glyph.xy;
-    vec2 glyphSize = glyph.zw;
-    vec2 uvOffset = uv.xy;
-    vec2 uvSize = uv.zw;
+    vec2 projectionOffset = projection.xy;
+    vec2 projectionScale = projection.zw;
 
-    // Position of cell from top-left
-    vec2 cellPosition = (cellDim) * gridCoords;
+    // Compute vertex corner position
+    vec2 position;
+    position.x = (gl_VertexID == 0 || gl_VertexID == 1) ? 1. : 0;
+    position.y = (gl_VertexID == 0 || gl_VertexID == 3) ? 0. : 1;
 
-    // Invert Y since framebuffer origin is bottom-left
-    cellPosition.y = termDim.y - cellPosition.y - cellDim.y;
+    // Position of cell from top-left
+    vec2 cellPosition = cellDim * gridCoords;
 
     if (backgroundPass != 0) {
-        cellPosition.y = cellPosition.y;
-        vec2 finalPosition = cellDim * position + cellPosition;
-        gl_Position = projection * vec4(finalPosition.xy, 0.0, 1.0);
+        vec2 finalPosition = cellPosition + cellDim * position;
+        gl_Position = vec4(projectionOffset + projectionScale * finalPosition, 0.0, 1.0);
+
         TexCoords = vec2(0, 0);
     } else {
-        // Glyphs are offset within their cell; account for y-flip
-        vec2 cellOffset = vec2(glyphOffset.x, glyphOffset.y - glyphSize.y);
+        vec2 glyphSize = glyph.zw;
+        vec2 glyphOffset = glyph.xy;
+        glyphOffset.y = cellDim.y - glyphOffset.y;
 
-        // position coordinates are normalized on [0, 1]
-        vec2 finalPosition = glyphSize * position + cellPosition + cellOffset;
+        vec2 finalPosition = cellPosition + glyphSize * position + glyphOffset;
+        gl_Position = vec4(projectionOffset + projectionScale * finalPosition, 0.0, 1.0);
 
-        gl_Position = projection * vec4(finalPosition.xy, 0.0, 1.0);
-        TexCoords = uvOffset + vec2(position.x, 1 - position.y) * uvSize;
+        vec2 uvOffset = uv.xy;
+        vec2 uvSize = uv.zw;
+        TexCoords = uvOffset + position * uvSize;
     }
 
-    background = backgroundPass;
     bg = vec4(backgroundColor.rgb / 255.0, backgroundColor.a);
     fg = textColor / vec3(255.0, 255.0, 255.0);
 }