rendering.c: fast cos from sin calculation, with lossy fast_sqrt()
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c59708d619
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@ -5,6 +5,7 @@
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#include "../textures.h"
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#include "../rendering.h"
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#include "../context.h"
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#include "../util.h"
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#include "quad_element_buffer.h"
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#include <stb_ds.h>
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@ -19,7 +20,7 @@
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* before anything is really rendered
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*/
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/* TODO: it might make sense to infer alpha channel presence / meaningfulness for textures in atlas */
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/* so that they are rendered with no blend / batched in a way to reduce overdraw automatically */
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/* so that they are rendered with no blend / batched in a way to reduce overdraw automatically */
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void push_sprite(char *path, t_frect rect) {
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struct sprite_primitive sprite = {
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.rect = rect,
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@ -104,7 +105,7 @@ static void render_sprites(const struct primitive_2d primitives[],
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const size_t len,
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const bool reversed)
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{
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/* single vertex array is used for every batch with NULL glBufferData() trick at the end */
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/* single vertex array is used for every batch with NULL glBufferData() trick at the end */
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static GLuint vertex_array = 0;
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if (vertex_array == 0)
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glGenBuffers(1, &vertex_array);
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@ -128,103 +129,104 @@ static void render_sprites(const struct primitive_2d primitives[],
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const size_t cur = reversed ? len - i - 1: i;
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const struct sprite_primitive sprite = primitives[cur].sprite;
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const t_rect srcrect =
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textures_get_srcrect(&ctx.texture_cache, primitives[cur].sprite.texture_key);
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const t_rect srcrect =
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textures_get_srcrect(&ctx.texture_cache, primitives[cur].sprite.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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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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/* non-rotated case */
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if (sprite.rotation == 0.0f) {
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payload[i] = (struct sprite_primitive_payload) {
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/* upper-left */
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.v0 = {
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sprite.rect.x,
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sprite.rect.y },
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.uv0 = {
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xr + wr * sprite.flip_x,
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yr + hr * sprite.flip_y, },
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/* non-rotated case */
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if (sprite.rotation == 0.0f) {
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payload[i] = (struct sprite_primitive_payload) {
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/* upper-left */
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.v0 = {
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sprite.rect.x,
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sprite.rect.y },
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.uv0 = {
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xr + wr * sprite.flip_x,
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yr + hr * sprite.flip_y, },
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/* bottom-left */
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.v1 = {
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(sprite.rect.x),
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(sprite.rect.y + sprite.rect.h) },
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.uv1 = {
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xr + wr * sprite.flip_x,
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yr + hr * !sprite.flip_y, },
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/* bottom-left */
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.v1 = {
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(sprite.rect.x),
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(sprite.rect.y + sprite.rect.h) },
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.uv1 = {
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xr + wr * sprite.flip_x,
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yr + hr * !sprite.flip_y, },
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/* bottom-right */
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.v2 = {
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(sprite.rect.x + sprite.rect.w),
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(sprite.rect.y + sprite.rect.h) },
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.uv2 = {
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xr + wr * !sprite.flip_x,
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yr + hr * !sprite.flip_y, },
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/* bottom-right */
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.v2 = {
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(sprite.rect.x + sprite.rect.w),
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(sprite.rect.y + sprite.rect.h) },
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.uv2 = {
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xr + wr * !sprite.flip_x,
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yr + hr * !sprite.flip_y, },
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/* upper-right */
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.v3 = {
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(sprite.rect.x + sprite.rect.w),
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(sprite.rect.y) },
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.uv3 = {
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xr + wr * !sprite.flip_x,
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yr + hr * sprite.flip_y, },
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/* upper-right */
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.v3 = {
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(sprite.rect.x + sprite.rect.w),
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(sprite.rect.y) },
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.uv3 = {
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xr + wr * !sprite.flip_x,
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yr + hr * sprite.flip_y, },
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/* equal for all (flat shaded) */
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.c0 = sprite.color,
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.c1 = sprite.color,
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.c2 = sprite.color,
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.c3 = sprite.color,
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};
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} else {
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/* rotated case */
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const t_fvec2 c = frect_center(sprite.rect);
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const t_fvec2 d = {
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.x = (cosf(sprite.rotation + (float)M_PI_4) * sprite.rect.w) * (float)M_SQRT1_2,
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.y = (sinf(sprite.rotation + (float)M_PI_4) * sprite.rect.h) * (float)M_SQRT1_2,
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};
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/* equal for all (flat shaded) */
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.c0 = sprite.color,
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.c1 = sprite.color,
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.c2 = sprite.color,
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.c3 = sprite.color,
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};
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} else {
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/* rotated case */
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const t_fvec2 c = frect_center(sprite.rect);
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const t_fvec2 t = fast_cossine(sprite.rotation + (float)M_PI_4);
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const t_fvec2 d = {
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.x = t.x * sprite.rect.w * (float)M_SQRT1_2,
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.y = t.y * sprite.rect.h * (float)M_SQRT1_2,
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};
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payload[i] = (struct sprite_primitive_payload) {
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/* upper-left */
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.v0 = {
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c.x - d.x,
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c.y - d.y },
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.uv0 = {
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xr + wr * sprite.flip_x,
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yr + hr * sprite.flip_y, },
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payload[i] = (struct sprite_primitive_payload) {
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/* upper-left */
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.v0 = {
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c.x - d.x,
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c.y - d.y },
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.uv0 = {
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xr + wr * sprite.flip_x,
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yr + hr * sprite.flip_y, },
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/* bottom-left */
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.v1 = {
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c.x - d.y,
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c.y + d.x },
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.uv1 = {
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xr + wr * sprite.flip_x,
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yr + hr * !sprite.flip_y, },
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/* bottom-left */
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.v1 = {
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c.x - d.y,
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c.y + d.x },
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.uv1 = {
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xr + wr * sprite.flip_x,
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yr + hr * !sprite.flip_y, },
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/* bottom-right */
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.v2 = {
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c.x + d.x,
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c.y + d.y },
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.uv2 = {
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xr + wr * !sprite.flip_x,
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yr + hr * !sprite.flip_y, },
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/* bottom-right */
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.v2 = {
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c.x + d.x,
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c.y + d.y },
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.uv2 = {
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xr + wr * !sprite.flip_x,
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yr + hr * !sprite.flip_y, },
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/* upper-right */
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.v3 = {
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c.x + d.y,
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c.y - d.x },
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.uv3 = {
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xr + wr * !sprite.flip_x,
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yr + hr * sprite.flip_y, },
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/* upper-right */
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.v3 = {
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c.x + d.y,
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c.y - d.x },
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.uv3 = {
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xr + wr * !sprite.flip_x,
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yr + hr * sprite.flip_y, },
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/* equal for all (flat shaded) */
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.c0 = sprite.color,
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.c1 = sprite.color,
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.c2 = sprite.color,
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.c3 = sprite.color,
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};
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}
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/* equal for all (flat shaded) */
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.c0 = sprite.color,
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.c1 = sprite.color,
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.c2 = sprite.color,
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.c3 = sprite.color,
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};
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}
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}
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glUnmapBuffer(GL_ARRAY_BUFFER);
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@ -12,57 +12,57 @@
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#include <string.h>
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bool infer_elf_section_bounds(const char *const restrict name,
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const char **restrict vm_start,
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const char **restrict vm_end)
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const char **restrict vm_start,
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const char **restrict vm_end)
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{
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bool result = false;
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char buf[PATH_MAX];
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ssize_t l = readlink("/proc/self/exe", buf, PATH_MAX);
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if (l == -1)
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goto ERR_CANT_READLINK;
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buf[l] = 0; /* readlink() doesn't write a terminator */
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bool result = false;
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char buf[PATH_MAX];
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ssize_t l = readlink("/proc/self/exe", buf, PATH_MAX);
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if (l == -1)
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goto ERR_CANT_READLINK;
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buf[l] = 0; /* readlink() doesn't write a terminator */
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int elf = open(buf, O_RDONLY);
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if (elf == -1)
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goto ERR_CANT_OPEN_SELF;
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int elf = open(buf, O_RDONLY);
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if (elf == -1)
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goto ERR_CANT_OPEN_SELF;
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/* elf header */
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Elf64_Ehdr ehdr;
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read(elf, &ehdr, sizeof ehdr);
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if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
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ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
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ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
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ehdr.e_ident[EI_MAG3] != ELFMAG3)
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goto ERR_NOT_ELF;
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/* elf header */
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Elf64_Ehdr ehdr;
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read(elf, &ehdr, sizeof ehdr);
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if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
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ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
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ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
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ehdr.e_ident[EI_MAG3] != ELFMAG3)
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goto ERR_NOT_ELF;
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/* section header string table */
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Elf64_Shdr shstrdr;
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lseek(elf, ehdr.e_shoff + ehdr.e_shstrndx * sizeof (Elf64_Shdr), SEEK_SET);
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read(elf, &shstrdr, sizeof shstrdr);
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char *sh = malloc(shstrdr.sh_size);
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lseek(elf, shstrdr.sh_offset, SEEK_SET);
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read(elf, sh, shstrdr.sh_size);
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/* section header string table */
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Elf64_Shdr shstrdr;
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lseek(elf, ehdr.e_shoff + ehdr.e_shstrndx * sizeof (Elf64_Shdr), SEEK_SET);
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read(elf, &shstrdr, sizeof shstrdr);
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char *sh = malloc(shstrdr.sh_size);
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lseek(elf, shstrdr.sh_offset, SEEK_SET);
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read(elf, sh, shstrdr.sh_size);
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/* walk sections searching for needed name */
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lseek(elf, ehdr.e_shoff, SEEK_SET);
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for (size_t s = 0; s < ehdr.e_shnum; ++s) {
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Elf64_Shdr shdr;
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read(elf, &shdr, sizeof shdr);
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/* walk sections searching for needed name */
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lseek(elf, ehdr.e_shoff, SEEK_SET);
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for (size_t s = 0; s < ehdr.e_shnum; ++s) {
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Elf64_Shdr shdr;
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read(elf, &shdr, sizeof shdr);
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if (strcmp(&sh[shdr.sh_name], name) == 0) {
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result = true;
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*vm_start = getauxval(AT_ENTRY) - ehdr.e_entry + (char *)shdr.sh_addr;
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*vm_end = getauxval(AT_ENTRY) - ehdr.e_entry + (char *)shdr.sh_addr + shdr.sh_size;
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break;
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}
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}
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if (strcmp(&sh[shdr.sh_name], name) == 0) {
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result = true;
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*vm_start = getauxval(AT_ENTRY) - ehdr.e_entry + (char *)shdr.sh_addr;
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*vm_end = getauxval(AT_ENTRY) - ehdr.e_entry + (char *)shdr.sh_addr + shdr.sh_size;
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break;
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}
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}
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free(sh);
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free(sh);
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ERR_NOT_ELF:
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close(elf);
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close(elf);
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ERR_CANT_OPEN_SELF:
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ERR_CANT_READLINK:
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return result;
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return result;
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}
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23
src/util.h
23
src/util.h
@ -154,5 +154,28 @@ void tick_ftimer(float *value);
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/* returns true if value was cycled */
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bool repeat_ftimer(float *value, float at);
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/* http://www.azillionmonkeys.com/qed/sqroot.html */
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static inline float fast_sqrt(float x)
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{
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union {
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float f;
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uint32_t u;
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} pun = {.f = x};
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pun.u += 127 << 23;
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pun.u >>= 1;
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return pun.f;
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}
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static inline t_fvec2 fast_cossine(float a) {
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const float s = sinf(a);
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return (t_fvec2){
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.x = fast_sqrt(1.0f - s * s) * (a >= (float)M_PI_2 && a < (float)(M_PI + M_PI_2) ? -1 : 1),
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.y = s
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};
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}
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#endif
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