a-game

commit a01886f8d79f123cd140c0aaf00be5b77b1d19d0
parent eac9fbb97e04eaad748ea858c21e894abb1defe4
Author: Amin Mesbah <dev@aminmesbah.com>
Date:   Sat, 20 Jul 2019 19:21:42 -0700

Don't use glTexStorage3D to allocate space

We want to require OpenGL 3.3, not 4.2.

Diffstat:
M
src/am_math.h
 | 
12
++++++++++++
M
src/render.c
 | 
11
++++++++++-

2 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/src/am_math.h b/src/am_math.h
@@ -17,6 +17,12 @@ internal inline f32 math_max(f32 a, f32 b)
     return max;
 }
 
+internal inline u32 math_pow_of_2(u32 exponent)
+{
+    u32 result = 1 << exponent;
+    return result;
+}
+
 internal inline i32 math_round(f32 n)
 {
     return n < 0.0f ? n - 0.5 : n + 0.5;
@@ -210,6 +216,12 @@ internal inline bool math_v2i_eq(v2i vec1, v2i vec2)
     return result;
 }
 
+internal inline bool math_v2u_eq(v2u vec1, v2u vec2)
+{
+    bool result = (vec1.x == vec2.x && vec1.y == vec2.y);
+    return result;
+}
+
 internal inline v3 math_v3_cross(v3 vec1, v3 vec2)
 {
     // cross product, a.k.a. outer product or vector product
diff --git a/src/render.c b/src/render.c
@@ -58,7 +58,16 @@ internal void renderer_init(struct RendererState *renderer, struct Image *images
         glGenTextures(1, &texture_id);
         glBindTexture(GL_TEXTURE_2D_ARRAY, texture_id);
         u32 mip_map_levels = 4;
-        glTexStorage3D(GL_TEXTURE_2D_ARRAY, mip_map_levels, GL_RGBA8, tile_dim.x, tile_dim.y, tileset_dim.x * tileset_dim.y);
+        // NOTE(amin): This allocates space for the 2D array texture. If we
+        // required OpenGL 4.2, we could instead use glTexStorage3D and no
+        // loop:
+        //     glTexStorage3D(GL_TEXTURE_2D_ARRAY, mip_map_levels, GL_RGBA8, tile_dim.x, tile_dim.y, tileset_dim.x * tileset_dim.y);
+        for (u32 level = 0; level < mip_map_levels; level++)
+        {
+            v2u mip_dim = {tile_dim.x / math_pow_of_2(level), tile_dim.y / math_pow_of_2(level)};
+            assert(!math_v2u_eq(mip_dim, (v2u) {0, 0}));
+            glTexImage3D(GL_TEXTURE_2D_ARRAY, level, GL_RGBA8, mip_dim.x, mip_dim.y, tileset_dim.x * tileset_dim.y, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
+        }
 
         size_t marker = mem_st_get_marker(allocator);
         {