Optimize Rendering with batched draw calls

Draw calls are now batched for performance. Render times on git log at
the default size are now ~200usec.

2 files changed, 18 insertions, 11 deletions

diff --git a/res/text.f.glsl b/res/text.f.glsl
index e817626f..d3265712 100644
--- a/res/text.f.glsl
+++ b/res/text.f.glsl
@@ -1,15 +1,17 @@
 #version 330 core
 in vec2 TexCoords;
+flat in int InstanceId;
 
 layout(location = 0, index = 0) out vec4 color;
 layout(location = 0, index = 1) out vec4 alphaMask;
 
 uniform sampler2D mask;
-uniform ivec3 textColor;
+uniform ivec3 textColor[32];
 
 void main()
 {
+    int i = InstanceId;
     alphaMask = vec4(texture(mask, TexCoords).rgb, 1.0);
-    vec3 textColorF = vec3(textColor) / vec3(255.0, 255.0, 255.0);
+    vec3 textColorF = vec3(textColor[i]) / vec3(255.0, 255.0, 255.0);
     color = vec4(textColorF, 1.0);
 }
diff --git a/res/text.v.glsl b/res/text.v.glsl
index c6543352..66bfad0c 100644
--- a/res/text.v.glsl
+++ b/res/text.v.glsl
@@ -2,6 +2,7 @@
 layout (location = 0) in vec2 position;
 
 out vec2 TexCoords;
+flat out int InstanceId;
 
 // Terminal properties
 uniform vec2 termDim;
@@ -9,33 +10,37 @@ uniform vec2 cellDim;
 uniform vec2 cellSep;
 
 // Cell properties
-uniform vec2 gridCoords;
+uniform vec2 gridCoords[32];
 
 // glyph properties
-uniform vec2 glyphScale;
-uniform vec2 glyphOffset;
+uniform vec2 glyphScale[32];
+uniform vec2 glyphOffset[32];
 
 // uv mapping
-uniform vec2 uvScale;
-uniform vec2 uvOffset;
+uniform vec2 uvScale[32];
+uniform vec2 uvOffset[32];
 
 // Orthographic projection
 uniform mat4 projection;
 
 void main()
 {
+    int i = gl_InstanceID;
+
     // Position of cell from top-left
-    vec2 cellPosition = (cellDim + cellSep) * gridCoords;
+    vec2 cellPosition = (cellDim + cellSep) * gridCoords[i];
 
     // Invert Y since framebuffer origin is bottom-left
     cellPosition.y = termDim.y - cellPosition.y - cellDim.y;
 
     // Glyphs are offset within their cell; account for y-flip
-    vec2 cellOffset = vec2(glyphOffset.x, glyphOffset.y - glyphScale.y);
+    vec2 cellOffset = vec2(glyphOffset[i].x,
+                           glyphOffset[i].y - glyphScale[i].y);
 
     // position coordinates are normalized on [0, 1]
-    vec2 finalPosition = glyphScale * position + cellPosition + cellOffset;
+    vec2 finalPosition = glyphScale[i] * position + cellPosition + cellOffset;
 
     gl_Position = projection * vec4(finalPosition.xy, 0.0, 1.0);
-    TexCoords = vec2(position.x, 1 - position.y) * uvScale + uvOffset;
+    TexCoords = vec2(position.x, 1 - position.y) * uvScale[i] + uvOffset[i];
+    InstanceId = i;
 }