118 lines
4.3 KiB
C
118 lines
4.3 KiB
C
/* a rendering.c mixin */
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#ifndef TRIANGLES_H
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#define TRIANGLES_H
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#include "../textures.h"
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#include "../context.h"
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#include <stb_ds.h>
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/* TODO: automatic handling of repeating textures */
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/* for that we could allocate a loner texture */
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void unfurl_triangle(const char *path,
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t_fvec3 v0,
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t_fvec3 v1,
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t_fvec3 v2,
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t_shvec2 uv0,
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t_shvec2 uv1,
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t_shvec2 uv2)
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{
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const t_texture_key texture_key = textures_get_key(&ctx.texture_cache, path);
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struct mesh_batch_item *batch_p = hmgetp_null(ctx.uncolored_mesh_batches, texture_key);
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if (!batch_p) {
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struct mesh_batch item = {0};
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hmput(ctx.uncolored_mesh_batches, texture_key, item);
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batch_p = &ctx.uncolored_mesh_batches[hmlenu(ctx.uncolored_mesh_batches) - 1]; /* TODO: can last index be used? */
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}
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union uncolored_space_triangle triangle = { .primitive = {
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.v0 = v0,
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.v1 = v1,
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.v2 = v2,
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.uv1 = m_to_fvec2(uv1),
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.uv0 = m_to_fvec2(uv0),
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.uv2 = m_to_fvec2(uv2),
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}};
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union uncolored_space_triangle *triangles =
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(union uncolored_space_triangle *)batch_p->value.primitives;
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arrpush(triangles, triangle);
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batch_p->value.primitives = (uint8_t *)triangles;
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}
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static void draw_uncolored_space_traingle_batch(struct mesh_batch *batch,
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t_texture_key texture_key)
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{
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size_t primitives_len = arrlenu(batch->primitives);
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if (primitives_len == 0)
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return;
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/* create vertex array object */
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if (batch->buffer == 0)
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glGenBuffers(1, &batch->buffer);
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/* TODO: try using mapped buffers while building batches instead? */
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/* this way we could skip client side copy that is kept until commitment */
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/* alternatively we could commit glBufferSubData based on a threshold */
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/* update pixel-based uvs to correspond with texture atlases */
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for (size_t i = 0; i < primitives_len; ++i) {
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struct uncolored_space_triangle_payload *payload =
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&((union uncolored_space_triangle *)batch->primitives)[i].payload;
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t_rect srcrect = textures_get_srcrect(&ctx.texture_cache, texture_key);
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t_rect dims = textures_get_dims(&ctx.texture_cache, texture_key);
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const float wr = (float)srcrect.w / (float)dims.w;
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const float hr = (float)srcrect.h / (float)dims.h;
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const float xr = (float)srcrect.x / (float)dims.w;
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const float yr = (float)srcrect.y / (float)dims.h;
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payload->uv0.x = xr + ((float)payload->uv0.x / (float)srcrect.w) * wr;
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payload->uv0.y = yr + ((float)payload->uv0.y / (float)srcrect.h) * hr;
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payload->uv1.x = xr + ((float)payload->uv1.x / (float)srcrect.w) * wr;
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payload->uv1.y = yr + ((float)payload->uv1.y / (float)srcrect.h) * hr;
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payload->uv2.x = xr + ((float)payload->uv2.x / (float)srcrect.w) * wr;
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payload->uv2.y = yr + ((float)payload->uv2.y / (float)srcrect.h) * hr;
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}
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textures_bind(&ctx.texture_cache, texture_key, GL_TEXTURE_2D);
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glBindBuffer(GL_ARRAY_BUFFER, batch->buffer);
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/* upload batched data */
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glBufferData(GL_ARRAY_BUFFER,
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primitives_len * sizeof (struct uncolored_space_triangle_payload),
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batch->primitives,
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GL_STREAM_DRAW);
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/* vertex specification*/
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glEnableClientState(GL_VERTEX_ARRAY);
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glVertexPointer(3,
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GL_FLOAT,
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offsetof(struct uncolored_space_triangle_payload, v1),
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(void *)offsetof(struct uncolored_space_triangle_payload, v0));
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glEnableClientState(GL_TEXTURE_COORD_ARRAY);
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glClientActiveTexture(GL_TEXTURE0);
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glTexCoordPointer(2,
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GL_FLOAT,
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offsetof(struct uncolored_space_triangle_payload, v1),
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(void *)offsetof(struct uncolored_space_triangle_payload, uv0));
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/* commit for drawing */
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glDrawArrays(GL_TRIANGLES, 0, 3 * (int)primitives_len);
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glDisableClientState(GL_TEXTURE_COORD_ARRAY);
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glDisableClientState(GL_VERTEX_ARRAY);
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/* invalidate the buffer immediately */
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glBufferData(GL_ARRAY_BUFFER, 0, NULL, GL_STREAM_DRAW);
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glBindBuffer(GL_ARRAY_BUFFER, 0);
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}
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#endif
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