feat!: distinguish between vec4 and trunc vec4

Some shaders call for a vec4 input attribute where you only write
to the first three values, relying on opengl's behaviour of populating
the W column with 1 for various types of matrix math. Other shaders
will want to writ to all 4 columns.

Since writing to all the columns is the more intuitive choice when
specifying an input attribute as vec4, that has been made the default,
while vec4_truncated is now the choice if you only want to write
3 out of the 4 values.

vec4_truncated is an awful name though and when a better one occurs to
me I will change it.

1 files changed, 4 insertions, 3 deletions

diff --git a/src/webgl.zig b/src/webgl.zig
index 934ae3c..fa4198c 100644
--- a/src/webgl.zig
+++ b/src/webgl.zig
@@ -30,7 +30,7 @@ const UniformInfo = struct {
 const AttributeInfo = struct {
     identifier: [:0]const u8,
     shader_name: []const u8,
-    kind: enum { f32, vec2, vec3, vec4 },
+    kind: enum { f32, vec2, vec3, vec4, vec4_truncated },
     instance_divisor: ?u16 = null,
 };
 
@@ -207,10 +207,11 @@ pub fn Program(
             const size = switch (attr_info.kind) {
                 .f32 => 1,
                 .vec2 => 2,
-                .vec3, .vec4 => 3,
+                .vec3, .vec4_truncated => 3,
+                .vec4 => 4,
             };
             const a_type = switch (attr_info.kind) {
-                .f32, .vec2, .vec3, .vec4 => .f32,
+                .f32, .vec2, .vec3, .vec4, .vec4_truncated => .f32,
             };
             const normalize = .false;
             const stride = 0;