townengine/src/rendering/twn_triangles.c

82 lines
2.9 KiB
C

#include "twn_rendering.h"
#include "twn_rendering_c.h"
#include "twn_engine_context_c.h"
#include "twn_textures_c.h"
#include <stb_ds.h>
/* TODO: automatic handling of repeating textures */
/* for that we could allocate a loner texture */
void unfurl_triangle(const char *path,
Vec3 v0,
Vec3 v1,
Vec3 v2,
Vec2sh uv0,
Vec2sh uv1,
Vec2sh uv2)
{
const TextureKey texture_key = textures_get_key(&ctx.texture_cache, path);
struct MeshBatchItem *batch_p = hmgetp_null(ctx.uncolored_mesh_batches, texture_key);
if (!batch_p) {
struct MeshBatch item = {0};
hmput(ctx.uncolored_mesh_batches, texture_key, item);
batch_p = &ctx.uncolored_mesh_batches[hmlenu(ctx.uncolored_mesh_batches) - 1]; /* TODO: can last index be used? */
}
union UncoloredSpaceTriangle triangle = { .primitive = {
.v0 = v0,
.v1 = v1,
.v2 = v2,
.uv1 = m_vec2_from(uv1),
.uv0 = m_vec2_from(uv0),
.uv2 = m_vec2_from(uv2),
}};
union UncoloredSpaceTriangle *triangles = (union UncoloredSpaceTriangle *)batch_p->value.primitives;
arrpush(triangles, triangle);
batch_p->value.primitives = (uint8_t *)triangles;
}
void draw_uncolored_space_traingle_batch(struct MeshBatch *batch,
TextureKey texture_key)
{
static VertexBuffer vertex_array = 0;
if (vertex_array == 0)
vertex_array = create_vertex_buffer();
const size_t primitives_len = arrlenu(batch->primitives);
/* nothing to do */
if (primitives_len == 0)
return;
const Rect srcrect = textures_get_srcrect(&ctx.texture_cache, texture_key);
const Rect dims = textures_get_dims(&ctx.texture_cache, texture_key);
const float wr = srcrect.w / dims.w;
const float hr = srcrect.h / dims.h;
const float xr = srcrect.x / dims.w;
const float yr = srcrect.y / dims.h;
/* update pixel-based uvs to correspond with texture atlases */
for (size_t i = 0; i < primitives_len; ++i) {
struct UncoloredSpaceTrianglePayload *payload =
&((union UncoloredSpaceTriangle *)batch->primitives)[i].payload;
payload->uv0.x = xr + ((float)payload->uv0.x / srcrect.w) * wr;
payload->uv0.y = yr + ((float)payload->uv0.y / srcrect.h) * hr;
payload->uv1.x = xr + ((float)payload->uv1.x / srcrect.w) * wr;
payload->uv1.y = yr + ((float)payload->uv1.y / srcrect.h) * hr;
payload->uv2.x = xr + ((float)payload->uv2.x / srcrect.w) * wr;
payload->uv2.y = yr + ((float)payload->uv2.y / srcrect.h) * hr;
}
specify_vertex_buffer(vertex_array, batch->primitives, primitives_len * sizeof (struct UncoloredSpaceTrianglePayload));
finally_draw_uncolored_space_traingle_batch(batch, texture_key, vertex_array);
}