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Move clipping of graphics into the shader using gl_ClipDistance

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This simplifies our code and also fixes the image distortion when
partially off screen reported in #6467
This commit is contained in:
Kovid Goyal
2023-07-16 11:14:05 +05:30
parent 5d3ba9d35e
commit ea03d1eb36
2 changed files with 11 additions and 32 deletions
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7
kitty/graphics_vertex.glsl
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@@ -1,5 +1,6 @@
out vec2 texcoord; out vec2 texcoord;
uniform vec4 src_rect, dest_rect; out float gl_ClipDistance[4];
uniform vec4 src_rect, dest_rect, viewport;
#define left 0 #define left 0
#define top 1 #define top 1
@@ -17,4 +18,8 @@ void main() {
ivec2 pos = vertex_pos_map[gl_VertexID]; ivec2 pos = vertex_pos_map[gl_VertexID];
texcoord = vec2(src_rect[pos.x], src_rect[pos.y]); texcoord = vec2(src_rect[pos.x], src_rect[pos.y]);
gl_Position = vec4(dest_rect[pos.x], dest_rect[pos.y], 0, 1); gl_Position = vec4(dest_rect[pos.x], dest_rect[pos.y], 0, 1);
gl_ClipDistance[left] = gl_Position.x - viewport[left];
gl_ClipDistance[right] = viewport[right] - gl_Position.x;
gl_ClipDistance[top] = viewport[top] - gl_Position.y;
gl_ClipDistance[bottom] = gl_Position.y - viewport[bottom];
} }

36
kitty/shaders.c
View File

@@ -469,49 +469,23 @@ draw_background_image(OSWindow *w) {
unbind_program(); unbind_program();
} }
static void
fit_image_in_viewport(GraphicsUniforms *u, ImageRenderData *rd, ImageRect viewport) {
// dest_rect: x: -1 to 1, y: 1 to -1. src_rect: x: 0 to 1 for both axes
ImageRect src_rect = rd->src_rect, dest_rect = rd->dest_rect;
const float img_width = dest_rect.right - dest_rect.left;
if (viewport.left > dest_rect.left) {
float frac = 1.f - (dest_rect.right - viewport.left) / img_width;
dest_rect.left = viewport.left;
src_rect.left += frac; // src_rect: left is 0 right is 1
}
if (viewport.right < dest_rect.right) {
float frac = 1.f - (viewport.right - dest_rect.left) / img_width;
dest_rect.right = viewport.right;
src_rect.right -= frac; // src_rect: left is 0 right is 1
}
const float img_height = dest_rect.top - dest_rect.bottom;
if (viewport.top < dest_rect.top) {
float frac = 1.f - (viewport.top - dest_rect.bottom) / img_height;
dest_rect.top = viewport.top;
src_rect.top += frac; // src_rect.bottom is 1 top is 0
}
if (viewport.bottom > dest_rect.bottom) {
float frac = 1.f - (dest_rect.top - viewport.bottom) / img_height;
dest_rect.bottom = viewport.bottom;
src_rect.bottom -= frac; // src_rect.bottom is 1 top is 0
}
glUniform4f(u->src_rect, src_rect.left, src_rect.top, src_rect.right, src_rect.bottom);
glUniform4f(u->dest_rect, dest_rect.left, dest_rect.top, dest_rect.right, dest_rect.bottom);
}
static void static void
draw_graphics(int program, ssize_t vao_idx, ImageRenderData *data, GLuint start, GLuint count, ImageRect viewport) { draw_graphics(int program, ssize_t vao_idx, ImageRenderData *data, GLuint start, GLuint count, ImageRect viewport) {
bind_program(program); bind_program(program);
glActiveTexture(GL_TEXTURE0 + GRAPHICS_UNIT); glActiveTexture(GL_TEXTURE0 + GRAPHICS_UNIT);
GraphicsUniforms *u = &graphics_program_layouts[program].uniforms; GraphicsUniforms *u = &graphics_program_layouts[program].uniforms;
glUniform4f(u->viewport, viewport.left, viewport.top, viewport.right, viewport.bottom);
glEnable(GL_CLIP_DISTANCE0); glEnable(GL_CLIP_DISTANCE1); glEnable(GL_CLIP_DISTANCE2); glEnable(GL_CLIP_DISTANCE3);
for (GLuint i=0; i < count;) { for (GLuint i=0; i < count;) {
ImageRenderData *rd = data + start + i; ImageRenderData *rd = data + start + i;
glBindTexture(GL_TEXTURE_2D, rd->texture_id); glBindTexture(GL_TEXTURE_2D, rd->texture_id);
for (GLuint k=0; k < rd->group_count; k++, i++) { for (GLuint k=0; k < rd->group_count; k++, i++) {
fit_image_in_viewport(u, rd, viewport); glUniform4f(u->src_rect, rd->src_rect.left, rd->src_rect.top, rd->src_rect.right, rd->src_rect.bottom);
glUniform4f(u->dest_rect, rd->dest_rect.left, rd->dest_rect.top, rd->dest_rect.right, rd->dest_rect.bottom);
glDrawArrays(GL_TRIANGLE_FAN, 0, 4); glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
} }
} }
glDisable(GL_CLIP_DISTANCE0); glDisable(GL_CLIP_DISTANCE1); glDisable(GL_CLIP_DISTANCE2); glDisable(GL_CLIP_DISTANCE3);
bind_vertex_array(vao_idx); bind_vertex_array(vao_idx);
} }