renderer/opengl: explicit texture options

This sets up for a couple improvments (see TODO comments) and also sets
the glyph atlas textures to nearest neighbor sampling since we can do
that now that we never scale glyphs.

pkg/opengl/Texture.zig

@@ -92,6 +92,30 @@ pub const Format = enum(c_uint) {
     _,
 };
 
+/// Minification filter for textures.
+pub const MinFilter = enum(c_int) {
+    nearest = c.GL_NEAREST,
+    linear = c.GL_LINEAR,
+    nearest_mipmap_nearest = c.GL_NEAREST_MIPMAP_NEAREST,
+    linear_mipmap_nearest = c.GL_LINEAR_MIPMAP_NEAREST,
+    nearest_mipmap_linear = c.GL_NEAREST_MIPMAP_LINEAR,
+    linear_mipmap_linear = c.GL_LINEAR_MIPMAP_LINEAR,
+};
+
+/// Magnification filter for textures.
+pub const MagFilter = enum(c_int) {
+    nearest = c.GL_NEAREST,
+    linear = c.GL_LINEAR,
+};
+
+/// Texture coordinate wrapping mode.
+pub const Wrap = enum(c_int) {
+    clamp_to_edge = c.GL_CLAMP_TO_EDGE,
+    clamp_to_border = c.GL_CLAMP_TO_BORDER,
+    mirrored_repeat = c.GL_MIRRORED_REPEAT,
+    repeat = c.GL_REPEAT,
+};
+
 /// Data type for texture images.
 pub const DataType = enum(c_uint) {
     UnsignedByte = c.GL_UNSIGNED_BYTE,

src/renderer/OpenGL.zig

@@ -356,6 +356,10 @@ pub inline fn textureOptions(self: OpenGL) Texture.Options {
         .format = .rgba,
         .internal_format = .srgba,
         .target = .@"2D",
+        .min_filter = .linear,
+        .mag_filter = .linear,
+        .wrap_s = .clamp_to_edge,
+        .wrap_t = .clamp_to_edge,
     };
 }
 
@@ -388,6 +392,16 @@ pub inline fn imageTextureOptions(
         .format = format.toPixelFormat(),
         .internal_format = if (srgb) .srgba else .rgba,
         .target = .@"2D",
+        // TODO: Generate mipmaps for image textures and use
+        //       linear_mipmap_linear filtering so that they
+        //       look good even when scaled way down.
+        .min_filter = .linear,
+        .mag_filter = .linear,
+        // TODO: Separate out background image options, use
+        //       repeating coordinate modes so we don't have
+        //       to do the modulus in the shader.
+        .wrap_s = .clamp_to_edge,
+        .wrap_t = .clamp_to_edge,
     };
 }
 
@@ -409,6 +423,10 @@ pub fn initAtlasTexture(
             .format = format,
             .internal_format = internal_format,
             .target = .Rectangle,
+            .min_filter = .nearest,
+            .mag_filter = .nearest,
+            .wrap_s = .clamp_to_edge,
+            .wrap_t = .clamp_to_edge,
         },
         atlas.size,
         atlas.size,

src/renderer/opengl/Texture.zig

@@ -16,6 +16,10 @@ pub const Options = struct {
     format: gl.Texture.Format,
     internal_format: gl.Texture.InternalFormat,
     target: gl.Texture.Target,
+    min_filter: gl.Texture.MinFilter,
+    mag_filter: gl.Texture.MagFilter,
+    wrap_s: gl.Texture.Wrap,
+    wrap_t: gl.Texture.Wrap,
 };
 
 texture: gl.Texture,
@@ -48,10 +52,10 @@ pub fn init(
     {
         const texbind = tex.bind(opts.target) catch return error.OpenGLFailed;
         defer texbind.unbind();
-        texbind.parameter(.WrapS, gl.c.GL_CLAMP_TO_EDGE) catch return error.OpenGLFailed;
-        texbind.parameter(.WrapT, gl.c.GL_CLAMP_TO_EDGE) catch return error.OpenGLFailed;
-        texbind.parameter(.MinFilter, gl.c.GL_LINEAR) catch return error.OpenGLFailed;
-        texbind.parameter(.MagFilter, gl.c.GL_LINEAR) catch return error.OpenGLFailed;
+        texbind.parameter(.WrapS, @intFromEnum(opts.wrap_s)) catch return error.OpenGLFailed;
+        texbind.parameter(.WrapT, @intFromEnum(opts.wrap_t)) catch return error.OpenGLFailed;
+        texbind.parameter(.MinFilter, @intFromEnum(opts.min_filter)) catch return error.OpenGLFailed;
+        texbind.parameter(.MagFilter, @intFromEnum(opts.mag_filter)) catch return error.OpenGLFailed;
         texbind.image2D(
             0,
             opts.internal_format,